How Steroids Changed Mlb

Known as America’s pastime, baseball is a game in which generations of children of all ages grow up playing in parks, streets, and alleyways throughout America. These same children grew up idolizing names such as Cy Young, Babe Ruth, Mickey Mantle, Jackie Robinson, and Hank Aaron. These men, as thousands of men before and after them, played in a league simply named Major League Baseball. Major League Baseball is rich in history with statistics and records dating back to 1873. Baseballchronology. com (n. d. ) provides this fact. However, as technology has advanced, so have the men who play this game. In the last 15 years athletes have become bigger, faster, and stronger making a game that is so difficult to play,look relatively easy. As a result records that have stood for many years are able to be shattered. Attendance has increased to record levels. Team owners and players are making record amounts of money. Unfortunately, along with these record accomplishments Major League Baseball is enjoying, the use of illegal drugs known as steroids are running rampant among the league’s players. Therefore, although players have become bigger, faster, and stronger, rampant steroid use among players of the last 15 years has changed the face of Major League Baseball negatively. Although it is true that steroids cannot improve a hitter’s hand-eye coordination, balance, or reflex, steroids can affect how hard a hitter hits a baseball. The harder one can hit a baseball the better the chance a hitter has of a getting a base hit. More hits lead to more runs scored, home runs hit, runs batted in by a single player. High statistics lead to Major League Baseball records that have stood for many years to be broken. A player will earn a high salary because of his accomplishments. He will have more of a fan base. This not only affects his pocket book, but the pocket book of the owner of the player’s baseball team because of the increased attendance the player generates. Higher attendance leads to higher television ratings. High television ratings affect Major League Baseball because the higher ratings are, the more the league could demand in a network television contract. With all these factors to consider it is easy to see why a player would use steroids despite the health risk, and why owners would overlook rampant steroid use in Major League Baseball. Thompson, Vinto, O’Keeffe, & Red, 2009 provides interesting facts on this subject. Rampant steroid use has a profound effect on Major League Baseball’s home run record book. Major League Baseball dates back to the late 1800s. An astonishing five of the top 11 home run hitters of all-time either are confirmed or suspected steroid users including the top home run hitter of all-time Barry Bonds. Next is the single home run record. Barry Bonds also owns this record. He hit an amazing 73 home runs in 2001. Barry Bonds surpassed Mark McGwire whom alone with Sammy Sosa became the only players in Major League Baseball history to hit more than 61 home runs in a single season. Mark McGwire and Sammy Sosa are both confirmed steroid users. Mark McGwire hit 70 home runs in 1998 and Sammy Sosa hit 66 that same year. Prior to 1998 only two players ever hit more than 60 home runs in a single season. They are Babe Ruth, who hit 60 home runs in 1927 and Roger Maris who hit 61 home runs in 1961. Sportscity. com/MLB/500-Home-Run-Club (2007-2010) provides homerun statistics. Neither, Babe Ruth nor Roger Maris are suspected or confirmed steroid users. Steroid use is a key factor in perhaps the greatest pitcher of all-time’s success. Roger Clemens pitched 24 seasons in Major League Baseball. He compiled 354 wins, ninth most in history, 4672 strikeouts, third most all-time, seven Cy Young Awards, most all-time, while winning two World Series. Clemens allegedly began taking steroids in 1998. His accuser, Brian McNamee, Roger Clemens personal trainer from the year 1998 through the year 2007, testified to a senate judiciary committee, under oath that Roger Clemens began taking steroids not only to bulk up his aging body, but to help aid recovery time in between games. For athletes, the benefits from steroids come in the form of accelerated recovery from injury and from workouts, allowing them to exercise harder and more frequently. For a pitcher, especially aging pitchers, steroids help them bounce back between games† (Thompson, Vinto, O’Keeffe, & Red, 2009, p. 32). Roger Clemens denies these accusations and even fi led a defamation lawsuit again Brian McNamee that was eventually thrown out of court. If Roger Clemens used steroids, would he have won 354 games, or struck out 4672 hitters? Would Roger Clemens have won two World Series championships and seven Cy Young awards? Unfortunately, baseball fans may never know whether or not Roger Clemens took steroids; therefore these fans will never know the answer to these questions. However, just the question itself brings doubt to the legitimacy of Roger Clemens’ records and accomplishments. Broken records are not the only way rampant steroid use changed the face of Major League Baseball. In 1994 a labor dispute between the players and the owners resulted in a work stoppage. For the first time in the league’s 123 year history, a player’s strike resulted in the cancellation of Major League Baseball’s playoffs and World Series. Prior to the strike of 1994 Major League Baseball’s popularity was at an all-time high. Attendance reached a record high 70,257,938 in 1993. The previous record was set in 1991 at 56,813,760. Unfortunately for Major League Baseball, attendance figures dropped dramatically following the strike. Attendance figures from 1995 through 1997reached an average of 57,911,768 per year. Nineteen ninety-eight was a completely different story. Attendance figures hit a record high of 70,601,147 in large part because of the homerun race between Mark McGwire and Sammy Sosa. Baseballchronology. om (n. d. ) provides statistical attendance facts. Television ratings reached an all-time high because of the large number of fans who wanted to watch every Mark McGwire and Sammy Sosa at bat. Major League Baseball’s popularity was again at an all-time high. Owners and players benefitted greatly because of the substantial increase in revenue. Although there were many rumors concerning steroid use among players in Major League Baseball; neither the Major League Baseball’s Players Association or Major League Baseball’s Owners cared to implement a steroid testing program. Rampant steroid use among Major League Baseball Players was just a rumor in 1998. If the two sides agreed to test for steroids and those test turned up positive results in some of the game’s biggest names, attendance would fall once again. This was simply too much of a risk. Owners decided to look the other way, hoping rumors would fade. Rampant steroid use among players has changed the face of Major League Baseball negatively. First, steroid use among players changed the face of Major League Baseball’s record book. Second steroid use among players help drive attendance up by captivating fans from around America who had no idea players were shattering records because of the use of an illegal substance. Third, steroids use among players helped players and owners line their pockets with millions of dollars in revenue this attendance increase generated. Finally, any accomplishment a player has achieved in the last 15 years is in question from fans of Major League Baseball because these fans do not know every player who used steroids. This is an unfortunate reality for players who achieved greatness through hard work; without the aid of any

Lord of the Flies: The Evil of Human Nature Essay

â€Å"However Simon thought of the beast, there rose before his inward sight the picture of a human at once heroic and sick(Golding 128). This quote from William Goldings novel, Lord of the Flies, effectively suggests that human beings are evil; which is also the main theme of the novel. In the novel, the major characters at the ending reinforce Goldings negative view of human nature. Golding provides his view of human nature very early in the novel. The island on which the boys land is described as a paradise with a variety of flora and fauna. Upon the boys landing, the tube carrying the boys causes a scar on the island. The intensity of the destruction caused by the scar is described: All round him the long scar smashed into the jungle was a bath of heat(Golding 11). However, the destruction does not stop there. Later, the boys burn down a large part of the island as a result of their carelessness. Here, Golding shows that humans cause destruction even if they did not mean to. He is almost suggesting that causing destruction is second nature to us humans. At the end of the novel, the destruction comes full circle when Jacks tribe burns down the entire island. The presence of the boys has completely changed the island from a beautiful paradise to a charred wreckage. Goldings pessimistic view of human nature is further expanded with the issue of hunting. As the novel progresses, Jacks level of obsession with hunting continues to escalate until the very end of the novel. It is interesting to note that although the island has an abundance of fruits and the boys can easily catch fish and crabs at the beach, Jack insists on hunting to get meat. Later on, he enjoys hunting as if it were a sport:His mind was crowded with memories; memories of the knowledge that had come to them when they had outwitted a living thing, imposed their will upon it, taken away its life like a satisfying drink(Golding 88). Jack hunts not with the sole intention to get meat, but he particularly enjoy exercising power over living creatures while hunting. This shows how much Jack enjoys having power; the power to control other beings. Throughout the novel, Jack does everything he can to gain the respect of the boys; to gain support for power. Later when he most of the boys join his tribe, Jack takes one last step to secure his position as chief of his tribe. He goes as far as to order his tribe to hunt and kill Ralph to eliminate the last threat to his position. Here, we can see that Jack has moved from hunting pigs to hunting humans. Thus, this shows how savage and evil man can be as he hunts even his own kin. Besides, these examples also show that humans have an unquenchable thirst for power that if not controlled, will blind us and take over our soul. In the novel, Golding uses Jack and his tribe to illustrate the effects of complete freedom to man. After Jacks tribe is formed, the members are no longer referred to as boys but as savages with Jack as their Chief. This is a direct reference to the boys regression into a primitive state of being. Jacks tribe also performs several primitive practices that are usually attributed as savage. First of all, they paint their faces and bodies to conceal themselves while hunting pigs. Next, they perform brutal killing of pigs:Roger found a lodgment point and began to push till he was leaning with his whole weight. The spear moved forward inch by inch and the terrifying squealing became a high-pitched scream. Then Jack found the throat and the hot blood spouted over his hands(Golding 168,169). Last of all, they give an offering, the pigs head, to the beast hoping it would not harm them. Thus, this shows that the boys do not understand the true nature of the beast. Their situation is similar to primitive man, who gave offerings to gods and idols to protect their own well-being from natural disasters they did not understand. It is during the presentation of the offering that Jack said: Sharpen a stick at both ends (Golding 169). Obediently, Roger sharpens a stick and Jack skewers the pigs head on one end of the stick and places the other into the ground. This statement is repeated again at the end of the novel. When Ralph asks Samneric of what Jacks tribe plan to with him once he was captured one of them replied, Roger sharpened a stick at both ends(Golding234). Although Ralph would hardly understand what the phrase means, the terrible truth becomes clear to the reader. Jacks tribe plans to behead Ralph and skewer his head on a stick sharpened at both ends as another offering to the beast. It is, by far, the most brutal display of human savagery. Without the eye of watchful adults, Jack and his tribe are uncontrollable; and Jack as their leader, has absolute power. Golding has written Lord of the Flies based on his experience in war. He realizes that war is the greatest act of human evil, for it takes the lives of innocent people and causes nothing but destruction. Therefore, it is fitting for Golding to highlight the effects of war in the novel to reinforce his pessimistic view of human nature. At the end of the novel, Golding leaves the reader with an image of a war ship, which is one of the many traces of war in the novel. If the reader examines the opening of the story, there are references to a war going on in the world, such as Piggys mention of the atomic bomb: Not them. Didnt you hear what the pilot said? About the atomic bomb? Theyre all dead(Golding 20). The reader discovers that the boys are stranded on the island because of the war. Besides that, another trace of the war is the dead parachutist. The boys mistake the dead parachutist for the beast. Ironically, the dead parachutist is the beast in the sense that he is connected to the war going on in the world outside and the beast is attributed to the evil in human nature. Even the boys have their very own war on the island. Therefore, the island could represent a microcosm of the outside world. Now, we return to the image of the war ship. The arrival of the ship allows the boys to be rescued. However, the ship only serves to remind the reader that although the boys are rescued, they are taken back to a war-torn world. After experiencing one war, the boys are being taken to another. The circle of destruction continues. To sum everything up, Golding effectively uses the main characters, especially at the ending, to prove that humans are more evil than good. The last page of the novel has one last scene of Ralph which summarizes the main themes of the novel. From his experience on the island, he is no longer an innocent child as he has been exposed to the evil nature of human beings and human savagery:And in the middle of them, with filthy body, matted hair, and unwiped nose, Ralph wept for the end of innocence, the darkness of mans heart, and the fall through the air of the true, wise friend called Piggy(Golding 248). Works citedGolding, William. Lord of the Flies. London: Faber and Faber, 1996.

America & Germany Essay

America never wanted to participate in World War 1, in fact in August 1914 when the war broke out in Europe; President Woodrow Wilson issued a declaration of neutrality. Preferring to remain isolated from the war, America tried to broker peace between the allies and the axis, the war was in Europe; America did not need to get involved. On May 7th 1915, German U-boats, patrolling in the Atlantic Ocean, fired torpedos at the British passenger ship Lusitania sinking her in 20 minutes. 128 Americans were killed. Woodrow Wilson, demanded that Germany stop attacking passenger ships, and declared that America was too proud to fight. Wilson also tried to mediate a compromise settlement but failed. He also repeatedly warned that America would not tolerate unrestricted submarine warfare, as it was in violation to American ideas of human rights. Wilson was under great pressure from former president Theodore Roosevelt, who denounced German â€Å"piracy† and Wilson’s cowardice. In January 1917, Germany announced it would destroy all ships heading to Britain. Although Wilson broke off diplomatic ties with Germany, he still hoped to avert war by arming merchant vessels as a deterrent. Nevertheless, Germany began sinking American ships immediately. On February 1917, British intelligence gave the United States government a decoded telegram from Germany’s foreign minister, Arthur Zimmerman that had been intercepted en route to his ambassador to Mexico. The Zimmerman Telegram authorized the ambassador to offer Mexico the portions of the Southwest it had lost to the United States in the 1840s if it joined the Central Powers. However, because Wilson had run for re-election in 1916 on a very popular promise to keep the United States out of the European war, he had to handle the telegram very carefully. Wilson did not publicize it at first, only releasing the message to the press in March after weeks of German attacks on American ships had turned public sentiment toward joining the Allies. Later, on 2 April 1917, Wilson asked Congress for a declaration of war and four days later all but six senators and fifty representatives voted for a war resolution. The Selective Service Act that was passed the following month, along with an extraordinary number of volunteers, built up the army from less than 250,000 to four million over the course of the conflict. General John Pershing was appointed head of the American Expeditionary Force (AEF) and led the first troops to France Then, on April 6th 1917, America declared war on Germany.

No topic Essay Example | Topics and Well Written Essays - 500 words - 14

No topic - Essay Example They are all similarly Caucasian in appearance, but they have different cultural traditions, and it is this social difference that is called ethnicity. These ethnic differences have been a part of American history from the beginning, because people from many different countries came over as immigrants and formed communities which carried on these original traditions. The bigger American culture is made up of elements from all those other cultures. The English view of race was very positive about white people, seeing them as conquering heroes, who had taken over lands as rulers, just as English companies took over India and other colonies. They saw other races as inferior, however, and this was very extreme in the case of Africa. African people were viewed as savages and they were exploited because the British had superior weapons. This treatment shows that the British thought of Africans as something less than human and this kind of attitude was brought over to America in the early days, and transferred also to the view that white Americans had of other groups, including all the native tribes and nations who were on the land before the Europeans arrived. The system of slavery began with the establishment of various kinds of colonies in the American territories. There were not enough white people to tend the fields and so a system of plantations was created, bringing African Americans as slaves to work in them. These people were brought by force. There were also many poor white people who voluntarily became slaves for a fixed period of time, because this gave them a chance to make a new life in America when they had failed to prosper in their home country. White people saw themselves as superior, and this is a social cause of slavery. Slaves were not allowed to decide about family matters like getting married, and having children, and they could not own property, or invest in their own education, making this a

The Impact of Environmental Management System on the Competitive Essay

The Impact of Environmental Management System on the Competitive Advantage of Organizations - Essay Example Several papers have been written over the years discussing the competitive advantages of the environmental model. Unfortunately, most of these papers are either too simplistic or cover only a single aspect of the environmental model. Thus, in-depth studies on EMS are of great value to the future developments of it being in the corporate world. While there is no dearth of literature on why and how adopting Environmental Management System (EMS) can be advantageous, no one has as yet analyzed the variously available kinds of literature to present a comprehensive view of what makes EMS competitive. This paper attempts to fill this knowledge gap by analyzing available literature. This analysis should give a comprehensive view of the various advantages of adopting EMS. Though attempts have been made to include as many journals as possible, including every available literature was beyond the scope of this paper. The analysis in this paper is limited to the most important literature on the i mpact of EMS on the competitive advantage of organizations. The remaining part of the report is divided into various sections, as follows: In section 2, a comprehensive literature review is undertaken in order to establish a theoretical background for studying Environmental Management System and determine key features of EMS with special reference to EMS as a competitive advantage for organizations. The research hypothesis is formulated accordingly. Section 3 deals with research methods and section 4 presents the findings revolving the research hypothesis, based on the qualitative research of the available literature. Then, in section 5, the research is concluded along with the limitations of the research. As mentioned, there is no dearth of literature on EMS and its competitive advantages. This is in part due to the ISO 14001 standard, a voluntary system which is an effective means of continuous environmental improvement for the organization.

CRJ-105 questions Essay Example | Topics and Well Written Essays - 250 words

CRJ-105 questions - Essay Example However, given the drug courts currently in operation and the success with which they have operated to date it is clear that they are the future for drug related crime. According to the National Institute of Justice, â€Å"As of June 2010, there were over 2500 drug courts operating throughout the U.S. More than half of these target adult offenders; others address juvenile, child welfare and different court case types.† (National Institute of Justice, 2011) Anything that can reduce crime while at the same time reducing the potential for recidivism of criminals and benefit the community at the same time is a positive approach within the modern criminal justice system. By integrating treatment programs into the sentencing of the individuals for the drug related crimes committed society will see a vast difference over time as well as the levels currently seen in the prison system will be reduced. According to one report, â€Å"A number of randomized and controlled experimental studies published in peer-reviewed journals have found that drug court graduates have significantly lower re-arrest rates†¦Ã¢â‚¬ (National Institute of Justice,

Sustainable Talent Management Assignment Example | Topics and Well Written Essays - 1500 words

Sustainable Talent Management - Assignment Example Many leaders experience challenges while trying to gain sustainable competitive advantage in the current dynamic business environment. Organizations have created an environment that supports talent management and advances peoples’ needs. This is with the intention of addressing challenges that may arise (Deb, 2005). It is vital for the performance management process to allow persons with the right talent to handle specific tasks at an appropriate time. Most organizations handle varied issues affecting the line executives and human resource professionals in their businesses. Organizations apply different management process to measure employee talents. This is apparent when measuring the organizational performance against pre-set objectives (Povah & Thornton, 2011). The process unites every actor within a given organization and draws attention on qualitative measures and quantitative objectives of an organization. The process applies a strategically oriented focus within the per formance management process that allows the talent management process to be effective. Organizations and businesses use different methods when measuring talents among the employees. Most managers accurately measure the talent of every candidate and employee in their organizations. This enables them match the best talent and job; furthermore, it encourages them to support, motivate, manage and develop talents among employees. Accurate talent measurement is significant because it enables employees to perform their task appropriately, increasing profit within organizations. The process is vital to an organization because it enables employees to understand their strength and weaknesses making them learn how adapt to the working environment (Deb, 2005). Organizations use different approaches such as conducting interviews, understanding leadership success factors and applying leadership review process when measuring the talents among employees. This usually takes place through random inte rviews or conducting reference calls (Berger, 2010). The leader then observes the behavior and traits of the involved individual as seen when he or she handles the job. Talents measurement may also focus on observing personal attributes and core skills. This helps the manager understand the benefits that an individual may bring to an organization. Analyze the key concepts related to the talent pools and the talent review process. The talent pool is a development process that focuses on the concept and principles within an organization. Initially, the organizations assert that every employee is a member of the talent pool. Consequently, the development of problem solving ability among individuals starts during the youth until maturity implying that everyone possesses an inherent potential of cognitive development over time (Berger, 2010). The main aim of the talent pool process is to analyze both the present and future roles played by an individual and their capabilities. This proces s has a line manager who is responsible for observing talents with the help of human resource who offers support. Managers conduct different functions such as coaching for employees to perform their current roles (Galagan, 2011). A retired manager plays a mentoring role by ensuring that subordinates conduct their roles fully. The managers and retired managers record the results

Ancient Art created between 30,000 BCE500 CE Essay

Ancient Art created between 30,000 BCE500 CE - Essay Example Masks in ancient Mexico came in all shapes and sizes. They ranged from those that depicted human faces to those that were almost supernatural. Specifically, this mask was associated with the site of Tlatilco in the Basin of Mexico. The mask was characterized by a twisted simian like face with simple, serpentine curves for ears, protruding eye sockets with crisply outlined eyelids and very broad eyebrows (Historical and Scientific Association of Vancouver, 1926). However, as seen from the picture above, the mask was too small to cover the entire face. It is worth noting that paired holes that appeared below the years suggest that the mask was being tied on the lower face or onto some bundle or sculpture. Basically, this art was important because it was a sign of transformation (Historical and Scientific Association of Vancouver, 1926). This piece of art was made during the late second millennium B.C. commonly described as fertility figurines, this art was depicted women (Historical and Scientific Association of Vancouver, 1926). The arts’ attenuated limbs and sometimes the disturbing facial features were interpreted to be a sign of abnormalities indicative of special access to the supernatural realm. However, such interpretations are not exclusive. Most of the details reflect regional traditions whereby facial and body treatments can be precisely recognized. This piece of work was meant to show a social status in the society. For example, the narrow eyes and mouth of the art can be regarded to a representation of the so-called pretty lady figures from Tlatilco (Historical and Scientific Association of Vancouver, 1926). Both the female figure and the mask were as a result of rich history of Mexico. They are both ceramic products, painted and well sculptured in a 3D format (Historical and Scientific Association of Vancouver, 1926). The color (brown) of the two pieces of art is the similar maybe because they are all products

Human resource management Essay Example | Topics and Well Written Essays - 750 words - 7

Human resource management - Essay Example Hofstede studied the attitudes and working values of more than 116,000 IBM employees working in over 40 countries. Using factor analysis of gathered data, Hofstede shows that there are five dimensions that could not be described with other factors. Based on his results, he argues that national culture has an effect on attitudes and values related to workers or employees. Every country chooses a specific management system; however, it cannot reflect the priorities of a nation. The system may prevail by a powerful subculture due to the ability to locate its staff at the high levels of the organisation. Therefore, a predominant subculture can maintain to create a cultural imperialism. The subject was discussed by cross-cultural researchers only from the perspective of the countrys dominance over the country and not from the perspective of cultures dominance over the other culture (McSweeney, 2002, 56). The issue of choosing appropriate levels of analysis is the most significant challenge facing Hofstede’s theory. McSweeney, (2002, 55) argues that any theory should be based on detailed description levels. Hofstede’s findings describe the features. They clarify some of the cultural and behavioural paradigms in organisation of different countries. Hofstede classified the five cultural dimensions as follows (Hofstede, 2001, 56): Power distance: Based on this dimension, countries are different in terms how they treat inequality. Some countries allow inequality to grow so that there is a difference in power and wealth. In such cultures, there is disagreement between subordinates and authority. Uncertainty avoidance: This is regarded with how society members deal with the future risk possibilities. The dimension describes attempts of society to attain a certain level where they feel they are in a conflicting situation. Cultures with high UAI consist of people who

Marketing Plan for Company G Research Paper Example | Topics and Well Written Essays - 2500 words

Marketing Plan for Company G - Research Paper Example This discussion stresses that consumers with comparatively higher income level are likely to purchase electronic appliances as they want to make their life more convenient, and they are ready to part with their money for that. Individual with higher income level are inclined towards trying new commodities and thus would be a prime source of company’s initial revenue from the newly launched product line. In addition to the income level, geography is another important factor. The company should focus its marketing activities in mostly the urban areas as compared to the rural. There are several other different bases for identification of the target market. It must be kept into consideration that one segmentation variable must be superior to another in the hierarchy of variables. Other variables for identification of target market would be age, gender, occupation, education, social class, buyer behavior and lifestyle. This paper declares that the product of the company can be divided into three categories namely convenience goods, shopping goods and specialty goods. Following is the classification of the products offered by the company. The marketing objective if the company G would be to create awareness in the market about the newly launch product line. The company would have to organize various promotion and advertising activities in order to provide adequate exposure to the new product. Price Marketing objective related to the price would be to promote the product based on the criteria that the prices have been set for customers belonging to different income level. The strategy will assist the company in increasing its customer base as it would increase the target market when people from different income classes are indulged in the buying of the company’s products. Place Since the company has established a sound consumer base of franchises in its target market, the

Comparison and Contrast of Main Characters Essay Example for Free

Comparison and Contrast of Main Characters Essay Nora and Tom are the main characters of two plays, the Doll House and the Glass Menagerie respectively. In comparing and contrasting these two characters, it is vital to analyze the plays and to gain and understanding of their personalities and relationships with other people. Nora is the wife of Torvald, and their marriage is characterized by the domination of Tovarld over Nora and her complacent passivity. As a wife during the late 1800s, it was typical of women to have been treated like children with little to no independence. However, it is the failure of Nora to remain stuck in her gender role as the immature ornament. Tom is the son of Amanda and the brother of Laura, and his position in the family is marked by the absence of his own father. Tom is expected to fully maintain the family, yet his youth and inexperience, coupled by his mother’s demanding exasperation, do not equip him to be a successful head of the household. In analyzing these two characters, it is interesting to note the ways in which Nora and Tom are similar and different in regard to gender roles and passivity. Gender Roles Passivity In regard to gender roles and passivity, it is clear that Nora and Tom are caught up in the expectations of other people and playing out stereotypical functions to an extreme degree. Nora herself describes her situation as a wife with no ambitions and blames her husband, saying, â€Å"I lived by performing tricks for you†¦ you and father have done me a great wrong†¦ it’s your fault that my life has been wasted† (Ibsen, 1890, 117). In this comment, one can see the full frustration of Nora in regard to her plight as a fully dependent wife. However, one could dispute her allegation that all of the culpability rests on the shoulders of her husband and not at all on herself. As far as Tom is concerned, he is stuck taking care of his mother and sister, when he would truly rather be making more of a life for himself, stating â€Å"I tried to leave you behind me, but I am more faithful than I intended to be† (Williams, 1999, 97). Tom expresses his irritation with the situation of him being expected to perform all of the duties as the head of the household, a role which he increasingly rejects. Similar to Nora, he finds himself playing a part which he does not want to be playing. However, a vital difference is that Tom takes responsibility for remaining passively in a role which does not suit him and does not try to place the full blame on other people. Conclusion Nora and Tom are both characters who find themselves doing the bidding of other people in response to social expectations, rather than following their instincts in living their lives more for themselves. While Nora finds herself shaming her husband for her life mistakes, Tom is more apt to shame himself. However, in the end, both characters are able to break free of the gender roles and passivity which have bound them all too closely and dependently to other people. Nora ends up leaving her husband, just as Tom ends up leaving his wife and mother. While Nora ends the play on a note of anger and full finger pointing, Tome ends the play with a sense of regret that he must leave his family. Nora and Tom are able to escape the oppressive forces in their lives, yet they have markedly different approaches to assigning fault. Works Cited Ibsen, H. (1890). A Dolls House. W. H. Baker. Williams, T. (1999). The Glass Menagerie. New Directions Publishing.

Herman Mudgett Essay Example for Free

Herman Mudgett Essay Problem Statement H. H. Holmes was dubbed the first male serial killer in the United States; however, his profile did not entirely fit the characteristics of a male serial killer. Should H. H. Holmes be considered a â€Å"Black Widow†? Purpose Imagine a killer who enjoyed torturing his victims with a variety of methods, but got paid for it. Meet Dr. H. H. Holmes or also known as â€Å"The Torture Doctor†. He was a serial killer who hit Chicago in the late nineteenth century. He killed with the intention of receiving money, mostly in the form of insurance claims. Criminologists have characterized this as a trait mostly belonging to female serial killers. It is â€Å"Black Widows† who kill relatives for the insurance money. Therefore Holmes should be classified as having similar characteristics to a â€Å"Black Widow† or that of a female serial killer. Findings Herman Webster Mudgett born May 16, 1861 to Levi and Theodate Mudgett in Gilmanton, New Hampshire had a privileged life. His family was wealthy and he was a bight child. (5) His household was run with a strict Methodist structure and his father was a violent alcoholic. He was bullied in school and in one instance forced to face a real skeleton which is believed to be the start of his fascination with corpses. (2) He became curious with Anatomy after that. Mudgett expressed a huge interest in medicine and was enrolled in the University of Michigan in 1882. He excelled in Chemistry and Anatomy and they seemed to be a natural talent for him. He was extremely eager to work on the cadavers. (2) He graduated in 1884. â€Å"This was a unique feature for a serial killer because most serial killers do not finish school.† (2) It is not because they are not intelligent enough; it is because they lack the motivation. This is where Mudgett was different; he had the persistence and motivati on to finish school. It was easier because it was something he did enjoy and it was a gateway for his early crimes. Mudgett would steal corpses from the medical school after making false insurance claims on a person, naming himself the beneficiary. He would distort the bodies making it look like an accident and then identify the body as the person he took the claim out on. (1) This is most likely the reason he stayed in school; he was making a profit. This is where he started using his alias Henry Howard Holmes or H. H. Holmes and Herman Mudgett would eventually cease to exist.(2) His crime spree and fascination with corpses would continue well after medical school. After a string of insurance fraud and traveling the country Holmes made it to Chicago. He began working at a drug store owned by an ill Dr. Holton in the neighborhood of Englewood. Holton died not long after and Holmes convinced Mrs. Holton to sign over the pharmacy to him and then she mysteriously disappeared. (5) While owning the drug store he continued to scam people sometimes selling false drugs and avoiding paying back his credit. (2) Holmes did enjoy making money and tricking people, but he wanted more. Holmes bought an estate on 63rd street and Wallace right across the street from the pharmacy that would later be called the â€Å"Murder Castle.† The construction of the building was very curious. Holmes was the architect and always kept a change of workers so he was the only one who ever knew the full structure of the building. (2) It was three stories with the ground floor belonging to commercial buildings including his relocated drug store. The top two were designated for his murderous fantasies. It had a labyrinth structure and consisted of false doors, windowless rooms, chutes, and trap doors. (5) The Castle â€Å"was equipped with secret passages, trapdoors, soundproof rooms, doors that could be locked from the outside, gas jets to asphyxiate victims, and a kiln to cremate the bodies.† (3) The basement is what held even worse horrors. There was a furnace big enough to hold a human body and huge acid baths. There were also tables where he could perform on the bodie s. (2) The Castle would open a door for Holmes to make even more money. Holmes was a man who would make money off of anything he could and his killings were no different. After he had tortured and killed he victims he would clean and mount their bones. In the basement â€Å"some were meticulously dissected, stripped of flesh, crafted into skeleton models† (5) He would then sell the skeletons to medical schools and doctor’s offices.(2) He had gained connections with these places, so no one questioned him. (5) He was living out his fantasies and making money off of it and now the perfect opportunity was about to come along. The 1893 World’s Columbian Exchange in Chicago would take place only a couple miles from Holmes’ home â€Å"The Castle.† The fair lasted from May to October. Holmes opened his building for the visitors and furnished and ran it like a hotel. â€Å"Unfortunately, some of his guests did not survive his hospitality.† (1) Just like most serial killers Holmes picked easy targets; tourists. Few people would know exactly where they were staying and it would be awhile before anyone reported them missing. However Holmes did differ from other male serial killers in that he did not stick to a type. Most of his victims did happen to be women, but he also killed children and men. Disappearances associated with the fair were linked to his castle (1) Outside of using his castle on unknowing tourists he was a seducer of women. Many of Holmes’ victims were women whom he had seduced and tricked into signing over their life savings. He usually employed females to work for him â€Å"many of whom were required as a condition of employment to take out life insurance policies for which Holmes would pay the premiums but also be the beneficiary† (5) and these women would later become his victims. Some of these women he killed where women who he had tricked in to giving him their property after they thought he was going to marry them. One example was Julia Conner and her daug hter Pearl. She was a mistress of Holmes and got pregnant. She demanded marriage and Holmes agreed if he could perform an abortion. Julia agreed, but mysteriously vanished along with her daughter. (2) He also promised Emiline Segrand marriage if she gave him her life savings. He sealed her in his vault where she suffocated to death. (2) He did have a marriage that actually went through, three in fact. He did have three marriages that all happened to coincide with each other. His first wife Clara Lovering was before he went to medical school. He filed for divorce at the time of his second wife, but it failed to go through. After he began using his alias H.H. Holmes he married Myrta Belknap in 1887. He lived with her and their daughter, Lucy, in Illinois for a while before he made it to Chicago. Holmes married is third wife, Georgiana Yoke, in 1894 after his killing spree in Chicago. Each one of these women never became one of Holmes’ victims and would live out their lives not knowing he was a serial killer till he was caught. (5) The only person who ever knew about what Holmes did was Benjamin Pitzel. Benja min Pitzel became associated with Holmes when Holmes was first constructing the Castle. Pitzel was a carpenter who was a drunkard that could never hold a job down. Holmes needed a right hand man who was tough and would do anything for money; Pitzel fit this description and had already committed petty crimes. (2) Pitzel was married with five children and needed to provide for his family, so he did what Holmes asked him to. Together Pitzel and Holmes committed lots of fraud and forgery. When Holmes was forced to leave Chicago because creditors were closing in Pitzel followed. They went cross country and continued to commit more fraud and other suspected killings under different aliases. (5) During one of these crimes Holmes was incarcerated for the first time in his life. Running low on money and needing to escape plan. Holmes and Pitzel concocted a plan where they would get Pitzel’s wife to take out an insurance claim on him and then they would fake Pitzel death. (5) Before they could get started on the scam Holmes was arrested for a different crime that landed hi m in a Texas jail. For some reason Holmes spilled his entire plan to his cellmate Marion Hedgepeth, a convicted train robber. Hedgepeth gave Holmes the name of a shady attorney in return for $500 of the money he got. (4) Holmes was shortly bailed out by his new wife Georgiana Yokes. (2) Holmes was now beginning to make mistakes and the law was going to catch up with him. Now Holmes could get on to finish the scam of faking Pitzel’s death, but Holmes did not fake it, he actually killed his longtime associate. This was most likely his plan all along; he wanted to get rid of loose ends. Holmes and his attorney, acquired from his former cell mate, identified the body. Mrs. Pitzel unknowing it to be her real husband split the money with the two men, but in the end Holmes ended up with most of her share. (2) Holmes was becoming paranoid and realizing that he was making mistakes. â€Å"Becoming concerned that the five Pitzel children might expose him, he went away with three of the children, eventually killing them.† (1) There was still one mistake out there that would lead to his demise. Almost two months after Pitzel’s body was found Hedgepeth, the former cellmate, sent information about the insurance fraud to police when he never received his compensation from Holmes. Police sent the Pinkertons, a private security guard and detective agency; on Holmes’ trail (5) What they discovered would be horrifying. Holmes was caught on November 17, 1894 in Boston. His only outstanding charge was on a horse theft and detectives needed more to hold him. It was only when his old custodian from the Castle informed the authorities that he was never allowed to clean the upper floors did they found out about his murders past by â€Å"uncovering Holmess efficient methods of committing murders and then disposing of the corpses.† (5) Along with Holmes’ vast array of obvious torture equipment, pieces of human bones were discovered. None of the murders were proven because of the lack of evidence except for four that of Benjamin Pitzel and his three children. Police tracked down the children’s bodies when chasing Holmes across the country. The two girls were found in Toronto and the boy in Indianapolis. (5) Holmes reign had come to an end. It was never discovered how many people H. H. Holmes had actually killed, but missing people and peculiar activity always seem to surround him not including the fact that he had a killing house. No one will ever be certain; the only person who may have known the true story was killed by Holmes. Also Holmes confessed his innocence until the day he was hung on May 7, 1896 at age 34. (2) Towards the end, however, he did come clean but his story always seemed to change. He did confess to 27 murders, but some researchers have suggested it exceeds 200. (3) The one confession he did seem to stick with was that he said he resembled the Devil. (2) Whatever the number Holmes was a serial killer who learned how to make a profit off of it. Conclusion Dr. H. H. Holmes’s characteristics did not fit that of a normal male serial killer. For starters he finished college unlike most of his predecessors. It might have been due to the fact that he had endless cadavers to work on or because he was planning his criminal career. Holmes also received monetary gain from most of his victims. He did enjoy seducing and killing victims, but his motives did involve receiving money. This is a trait often associated with female serial killers. Criminologists distinguish traits from male and female serial killers. One of the traits associated with females is that their motives usually involve monetary gain. The â€Å"Black Widow† is a female serial killer who kills her husband or other relatives to receive the insurance money. Holmes fits this description because most of his victims were women whom he had seduced and promised marriage or employees after receiving rights to their property. Holmes fits characteristics of both genders, but the profile of a Male Black Widow fits him more than anything. Recommendations Holmes should be classified as a â€Å"Black Widow† even though he is a male. It is true the biggest trait of a â€Å"Black Widow† is the female part, but gender should not be as important as motive. Gender unconsidered Holmes clearly fit the description. Therefore criminologist might reconsider classifying primarily on gender. Looking primarily at gender leaves gaps and flukes that do not seem to fit the â€Å"normal† stereotype in profiling and Holmes proves that. Holmes is a â€Å"Black Widow.† Bibliography (1) H.H. Holmes. 2012. Biography.com 18 Apr 2012, 06:28 http://www.biography.com/people/h-h-holmes-307622 (2) H. H. Holmes Americas First Serial Killer. Dir. John Borowski. Waterfront Productions, 2004. Documentary. (3) John Philip, Jenkins. Mudgett, Herman Webster. Britannica Biographies (2011): 1. MasterFILE Premier. Web. 18 Apr. 2012 http://ezproxy.scottsdalecc.edu:2309/ehost/detail?sid=87fc7c73-9859-4344-a053-88394e30cdd1%40sessionmgr15vid=4hid=13bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#db=f5hAN=32418760 (4) Martin, John B. The Master of the Murder Castle: A Classic of Chicago Crime. Harpers Magazine. Harpers Magazine Foundation, Dec. 1943. Web. 18 Apr. 2012. http://www.harpers.org/archive/1943/12/0020617. (5) Wikipedia contributors. H. H. Holmes. Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 16 Apr. 2012. Web. 18 Apr. 2012. http://en.wikipedia.org/wiki/H._H._Holmes

Culture Of Hepg2 Cells Biology Essay

Culture Of Hepg2 Cells Biology Essay Hep G2 cell line was purchased from American Type Culture Collection (ACTT) (VA, USA). Dulbeccos Modified Eagle Medium (DMEM), 0.5% Trypsin-EDTA 10x, and Penicillin-Streptomycin (PS) were obtained from Invitrogen Corporation (NY, USA). Fetal Bovine Serum (FBS) was gotten from Welgene Inc. (Daegu, South Korea). Fatty acids (Palmitic, Oleic and Dedocanoic acid), Dimethyl sulfoxide (DMSO) and Tween 20 came from Sigma (MO, USA). Bovine serum albumin (BSA) was from Santa Cruz Biotechnology (CA, USA). MTT assay (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay) was purchased from Molecular Probes (Oregon, USA). LDH assay (Lactate dehydrogenase assay) was from ROCHE (Mannhein, Germany). [emailprotected]/503 and Carboxyl-H2DCFDA were purchased from Invitrogen Corporation (Oregon, USA). Nile red was from Fluka (MO, USA). Triglyceride Quantification Kit and ATP Colorimetric/Flourometric Assay Kit were purchased from BioVion Inc. (CA, USA). Annexin V Floustaining kit was from Roche (IN, USA). Phosphate buffered saline was made up of chemicals at pH 7.4, including 11.7g NaCl, 5.5g Na2HPO4-7H2O, and 1.35g NaH2PO4. All other chemicals met in standard grade of analysis. Culture of HepG2 cells HepG2 cells were cultured in Dulbeccos modified Eagles medium, containing 10% (v/v) fetal bovine serum and 1% (v/v) Penicillin-Streptomycin under 5 % CO2, 95 % humidity at 37 °C. The cells were subcultured by using 0.5% Trypsin-EDTA 1x (Invitrogen Corporation, NY, USA) for detachment and seeded at proper cell number in all experiments. Fatty acid treatment When 80 % confluency of HepG2 was reached, it was treated with various concentrations of the fatty acids (0 mM, 0.1 mM, 0.2 mM, 0.3 mM, 0.5 mM, 0.7 mM and 1.0 mM) for 24 h. The stock solution of fatty acids was prepared at 100 mM by dissolving in DMSO and stored at -200C. The stocks were diluted in DMEM media containing a constant ratio of fatty acid bound bovine serum albumin at 2 to 1 to obtain working solution in all experiments. Cytotoxicity assay Cytotoxicity was based on the measurement of cytoplasmic enzyme activity by using cytotoxicity detection kit (ROCHE, Mannhein, Germany). The cytoplasmic enzyme was released from damaged cells that its enzyme activity expresses to the proportion of toxiced-cell. Lactate dehydrogenase (LDH) presents in all cells which is a stable cytoplasmic enzyme. When the membrane integrity of the cells is damaged, it is quickly released into the media. In this assay, NAD+ is reduced to NADH/H+ during conversion of lactate to pyruvate by the LDH-catalyzed. After that, H/H+ from NADH/H+ was transferred by the catalyst (diaphorase) to the tetrazolium salt (yellow) which was reduced to formazan (red). To conduct the assay, the culture supernatant is collected cell-free after desire exposure time (24 h). The reaction mixture from the kit was then applied in the samples. The absorption of the formazan dye formed was measured at 490 nm on an ELISA reader (VERSARMAX, Molecular Divices., CA, USA). Cell viability Cell viability was measured based on measurement absorption of a water-insoluble purple formazan which was reduced from a yellow water-soluble tetrazolium salt in live cells. Briefly, the cells were treated with MTT (5 mg/ml) in DMEM at 37 0C for 1.5 h. Then, the media were removed, and DMSO was added to dissolve the furmazan crystals. After gently pipetting, the absorbency was measured at 570 nm using an ELISA reader (VERSARMAX, Molecular Divices., CA, USA). The estimation of cell viability was calculated by comparing between the spectra value of treated and untreated cells. Quantification of triglyceride Triglyceride content (TG) was determined according to an enzymic method (BioVion Inc, CA, USA). In this method, glycerol is a product by TG-catalyzed which reacts with the probe to generate coloration measured on spectrophotometry at 570 nm. In briefly, the cells were washed twice times with cold PBS, then homogenized in 5% Triton-X100 solution. After slowly heating at 80-100 °C for 5 min, the samples were centrifuged at 12000 rpm for 5 min. The supernatant collected from removing insoluble materials was added 2 ÃŽ ¼l of lipase, mixed well and incubated for 20 min at room temperature. Finally, 50 ÃŽ ¼l of the reaction mix was putted in each sample for 45 min of incubation, protected from light. The value of triglyceride content was quantified based on triglyceride standard curve that was constructed with different concentrations of TG (0, 20, 40, 60, 80, and 100 nmol/ml). Measurement of reactive oxygen species (ROS) generation The measurement of ROS production within cells was carried out by using 2†²,7†²-Dichlorohydrofluorescein diacetate (Carboxyl-H2DCFDA; Invitrogen Corporation, Oregon, USA) which is combined into fluorescent products in the presence of H2O2 and other ROS molecules and esterases (Zhenyuan Song et al, 2007). After the cells were overloaded with 1.0 mM fatty acids, 10 mM final concentration of Carboxyl-H2DCFDA was added in the media without FBS at 370C in darkness for 30 min. Then, the cells were washed twice times with warmed PBS and lysed in 200 Ã‚ ­l RIPA buffer (PIERCE, IL, USA). The lysed-cells were centrifuged at 12000 rpm for 5 min. The supernatants were conveyed to a 96-well back plate which were excited at 485 nm and emitted at 530 nm for the Carboxyl-H2DCFDA fluorescence on Fluorometer (VICTOR2, Perkin Elmer., MA, USA). Trilyceride staining on Confocal Bodipy @493/503 (Invitrogen, Oregon, USA) was used to capture TG fluorescence on Confocal microscopy. In this experiment, the cells were prepared as above. Before the dyes treatment, the cells were washed with PBS twice times. Bodipy @493/503 was then added at 1.0  Ã‚ ­M, and 15 min of incubation at 370C after the cells were rinsed with PBS again. Zeiss LSM Image Brown software (LSM 510 meta, Carl Zeiss., Jena, Germany) was handled to take TG image at excitation of 488 and emission of BP 505-530 nm. ROS staining on Confocal ROS generation in HepG2 was stained by using Carboxyl-H2DCFDA. In this experiment, the cells were prepared as above. Before the dyes treatment, the cells were washed with warmed PBS twice times. The carboxyl-H2DCFDA was applied at 10 mM final concentration in Serum free media (DMEM without FBS), and incubated for 30 min at 370C, protected from the light. After that, the cells were rinsed with warmed PBS again. Zeiss LSM Image Brown software (LSM 510 meta, Carl Zeiss., Jena, Germany) was handled to take ROS image at excitation of 488 nm and emission of LP 530 nm. Detection of cell death and trilyceride accumulation by Confocal HepG2 seeded in the 24-well plate and treated with final concentration of fatty acids to 1.0 mM for 24 h. After the incubation time, the cells were washed twice times with PBS. Then, Bodipy @493/503 (Invitrogen, Oregon, USA) was dissolved in PBS at 5  Ã‚ ­g/ml which was added into each well. This process was kept in darkness for 15 min at 370C. After that, the Bodipy solution was removed and the cells were then washed by Binding buffer from Annexin V Floustaining kit (Roche, IN, USA). Finally, the cells were incubated in 100  Ã‚ ­l/ml of Propidium iodide (PI) for 10 min in darkness. Exposition of TG accumulation and apoptosis was observed at excitation of 488 and 543 nm, and emission of BP 505-530 and LP 650 nm on Carl Zeiss Confocal Microscopy (LSM 510 meta, Carl Zeiss., Jena, Germany), respectively. Data analysis All results were expressed as mean of repeated three or four values  ± SEM. The difference between groups was identified by using t.test. p < 0.05 was considered statistical significant.

Comparing Two Advertisements :: Adverts, Compare and Contrast

Comparing Advertisements For this comparison I have chosen to compare two car adverts. The first advert I chose was from the car magazine "Autocar" and this is an advert for a Chrysler PT Cruiser. The second advert I chose was from the "Sunday Times" and this is for a Fiat Ulysse. I chose these two adverts because I feel that they will be good compare as they have similarities and differences so there are many things I can comment about. There is a big difference in the sale tactics of the 2 adverts. The Fiat is a soft sell advert because there is no reference to the price of the car or any statistics about the car where as the Chrysler advert displays the price in big numbers at the top of the advert and it also refers to the fuel consumption of the car. This shows that the 2 adverts use different tactics to advertise and sell the car. I think that the target audience for these cars are the same; both of these cars are family cars. Both of the cars are designed to be comfortable and safe, they are not advertised to be fast sports cars or stylish city cars; they are advertised as normal cars. In both of the adverts there is no real reference towards the performance of the car apart from in the Chrysler where there is a reference to the fuel consumption of the car but this backs up the point that the Chrysler is a car for a sensible family person because that is the kind of person who would show interest in the economics of the car. Both of the adverts have main points that they want you to focus on as soon as you look at them, on the Chrysler advert the first thing they want you to focus on is the name of the car and the price which are both in bold font at the top of the page, the Fiat wants you to focus on the name of the car which is written in huge letters diagonally

Carrion Comfort by Gerard Manley Hopkins Essay -- Carrion Comfort Hopk

Carrion Comfort by Gerard Manley Hopkins Gerard Manley Hopkins was a talented poet, and he was also extremely devoted to his faith. He used his poetry as an avenue in which to express his love and praise to his Creator, and many of his poems are beautiful hymns of adoration. â€Å"Carrion Comfort,† however, is one of his â€Å"terrible sonnets.† Hopkins not only wrote about the beautiful part of faith, but also the questioning and suffering that inevitably comes during a person’s spiritual journey. The Petrarchan or Italian sonnet was one of Hopkins’s favorite forms of poetry and one that he employed frequently in his writing. Hopkins enjoyed the fusion of form and content, and the structure of an Italian sonnet perfectly lends itself to such a synthesis. An Italian sonnet is divided into two parts, the octave and the sestet. The first eight lines have an ABBAABBA rhyme scheme and the sestet concludes with CDCDCD. The content of an Italian sonnet is very specifically and thematically organized as is the content of Hopkins’s â€Å"Carrion Comfort.† The octave is divided into two quatrains, which present and then develop, respectively, a problem or situation on which the poem focuses. The sestet relates the answer or solution to the problem. The transition between the two sections of the poem can be easily identified through dramatic punctuation, or a distinct change in tone. The octave in â€Å"Carrion Comfort† powerfully illustrates intense s uffering and despair experienced by the speaker. Hopkins masterfully depicts the transformation from the utter despair caused by this suffering to hope and reconciliation with God as he makes a transition into the sestet. Throughout the poem, Hopkins uses various poetic elements, such as th... ...feast on thee; Not untwist--slack they may be--these last strands of man In me or, most weary, cry I can no more. I can; Can something, hope, wish day come, not choose not to be. But ah, but O thou terrible, why wouldst thou rude on me Thy wring-world right foot rock? lay a lionlimb against me? Scan With darksome devouring eyes my bruised bones? and fan, O in turns of tempest, me heaped there; me frantic to avoid thee and flee? Why? That my chaff might fly; my grain lie, sheer and clear. Nay in all that toil, that coil, since (seems) I kissed the rod, Hand rather, my heart lo! lapped strength, stole joy, would laugh, cheer. Cheer whom though? The hero whose heaven-handling flung me, foot trod Me? or me that fought him? O which one? is it each one? That night, that year Of now done darkness I wretch lay wrestling with (my God!) my God.

Turning Points in History :: essays research papers fc

Turning Points in History   Ã‚  Ã‚  Ã‚  Ã‚  Turning points in history can mean a change in the way the things are done in the past, sometimes for the better, and other times for the worse. Two notable turning points in history were the Industrial Revolution and also World War I. These both had some political, social and cultural impacts.   Ã‚  Ã‚  Ã‚  Ã‚  The Industrial Revolution was a time of great change and increased efficiency. No more would be goods be produced by sole means of farming and agriculture, but now by the use of machinery and factories. Technology was beginning to increase along with the food supply as well as the population. However, this increase in population would greatly impact the social aspect of that time. Urbanization was becoming much more widespread. Cities were becoming overwhelmingly crowded and there was an increase in disease as well as harsh child labor. Although child labor would be reduced somewhat due to unions, the Industrial Revolution still contained both it’s positive and negative results.   Ã‚  Ã‚  Ã‚  Ã‚   World War I was another major turning point in history. This turning point consisted in the way war was fought and how it has changed due to the advances in technology that took place during this time in the 1900’s. War was triggered in the Balkans where the Ottoman Empire had once maintained control. Industrialization and technology had both contributed to the advances in the development of weapons. This devastatingly was the cause of millions of deaths in World War I. War was now fought in trenches and they used machine guns as well as tanks and grenades. There was definitely a turning point in the way war would be fought. However, the most important turning point in the war had to be the involvement of the US. The US tried to remain neutral in the war but ended up joining the Allies. Thanks to the US’s involvement, however, the Allies received the help needed to win the war.   Ã‚  Ã‚  Ã‚  Ã‚  In conclusion we can see that revolutions and wars can lead to positive and negative turning points.

Of Mice and Men Character Analysis: Loneliness Essay

In Of Mice and Men many characters are lonely or at least act that way. The characters I think are lonely are Lennie, George, Candy, Crooks, and Curley’s Wife. The loneliness in the story is what causes most of the conflict in the story. Everyone in this story is lonely or must have been lonely. I think loneliness is one of the most important parts of this story. Lennie is one of the loneliest characters in the book. He makes friends with animals, he likes to pet them and talk to them even if they are dead. Him being lonely even caused him to get trouble in weed. As a bright side to it, as result he meets his best friend, George, who helps him through the rest of the story. It is truly the best relationship throughout the whole book. Lennie however is still lonely with George. When they get to their new job he gets into even more trouble due to his loneliness; first killing his pup followed by doing the same to Curley’s Wife. Crooks is lonely, however I think he probably most times is just overlooked. No one wants to be with him because of his race. This does take place when there was still segregation. Even his room is set aside from the rest. While everyone sleeps in the bunk house he sleeps out in the stable with the horses. Then one of the only times they spend time with Crooks, in my opinion, was not a pleasurable experience for him. Candy had his dog. Which he must have really liked and he must have had it for a long time because when everyone else was sick of the dog he still kept him around. This is why I think Candy was sad during the duration of the story or before. Eventually he does let go of the dog but he can’t even kill it. Curley’s wife always acts like she is lonely. I say she is most likely acting because there is a possibility that she is the kind of narcissistic person who always needs more and more attention. She is always â€Å"looking for Curley† and she ends up mainly just taking to whoever she finds. She even goes as far as to offer Lennie to feel her hair. At one point at her life she even had the chance to become an actress where she would have been able to reach the maximum level for attention. She had this once in a life time opportunity stripped from her by her mother. That’s why I believe she feels she needs all the attention she actively seeks out. George in the story has only one true friend, Lennie. This friendship is only out of pity, but I don’t think George would purposefully abandon Lennie. George keeps Lennie in good standing with other people and tries to keep him out of trouble. George does get along with the other characters but I don’t think any of them really are a true friendship like what he has with Lennie. The loneliness progress the story like so. Lennnie’s solitude and love to feel soft things causes the accident in Weed with the girl’s dress. George’s seclusion, supervision, and companionship with Lennie grounds George to be entangled with him. Lennie again being desolate makes him ask George for one of Slim’s pups. He kills this pup on accident after it bites him. He is sitting in the barn thinking about what he had done and even talks to the deceased puppy. Curley’s wife finds him in the barn and in a way tries to comfort him. Lennie being the rough person he unfortunately is kills her on accident. All of these events were product of someone feeling alone. As this paper has thoroughly shown most of the characters in Of Mice and Men where lonely and were at one point in their life. All of the conflict originates in someone’s search for attention, love, or friendship. That the main component at the core of the story is loneliness.

Time to Digital Converter Used in All Digital Pll

Master Thesis ICT Time to Digital Converter used in ALL digital PLL Master of Science Thesis In System-on-Chip Design By Chen Yao Stockholm, 08, 2011 Supervisor: Dr. Fredrik Jonsson and Dr. Jian Chen Examiner: Prof. Li-Rong Zheng Master Thesis TRITA-ICT-EX-2011:212 1 ACKNOWLEDGEMENTS I would like to thank: Professor Li-Rong Zheng for giving me the opportunity to do my master thesis project in IPACK group at KTH. Dr. Fredrik Jonsson for providing me with the interesting topic and guiding me for the overall research and plan. Dr.Jian Chen for answering all my questions and making the completion of the project possible. Geng Yang, Liang Rong, Jue Shen, Xiao-Hong Sun in IPACK group for the discussion and valuable suggestions during the thesis work. My mother Xiu-Yun Zheng and my husband Ming-Li Cui for always supporting and encouraging me. i ABSTRACT This thesis proposes and demonstrates Time to Digital Converters (TDC) with high resolution realized in 65-nm digital CMOS. It is used as a phase detector in all digital PLL working with 5GHz DCO and 20MHz reference input for radio transmitters.Two kinds of high resolution TDC are designed on schematic level including Vernier TDC and parallel TDC. The Sensed Amplifier Flip Flop (SAFF) is implemented with less than 1ps sampling window to avoid metastability. The current starved delay elements are adopted in the TDC and the conversion resolution is equal to the difference of the delay time from these delay elements. Furthermore, the parallel TDC is realized on layout and finally achieves the resolution of 3ps meanwhile it consumes average power 442 µW with 1. 2V power supply. Measured integral nonlinearity and differential nonlinearity are 0. LSB and 0. 33LSB respectively. Keywords: All Digital PLL, Time to Digital Converter (TDC), Sensed Amplifier Flip Flop (SAFF), Current Starved, Vernier delay line ii Contents ACKNOWLEDGEMENTS †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. i LIST OF FIGURES†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. iv LIST OF TABLES †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. 1. 2. Introduction †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚ ¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. 1 State of art †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦ 4 2. 1 2. 2 2. 3 2. 4 3 Buffer delay line TDC†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. 4 Inverter delay line TDC †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. Vernier TDC †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. 5 Gated ring oscillator (GRO) TDC †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. 6 System level design †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. 7 3. 1 3. 2 3. 3 3. 4 Goal †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦ Vernier delay line TDC †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦ 9 Parallel TDC †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. 10 Performance comparison †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. 11 4 Schematic design and simulation †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦ 12 4. 1 Sense Amplifier Based Flip-Flop â € ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. 2 Schematic design†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦ 14 Sampling window simulation †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. 16 4. 1. 1 4. 1. 2 4. 2 Vernier delay line TDC †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. 21 Delay cells †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦ 21 Simulation results †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. 5 4. 2. 1 4. 2. 2 4. 3 Parallel TDC †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦ 28 Delay cells †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦ 28 Simulation results †¦Ã¢â‚¬ ¦Ã¢â ‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. 30 4. 3. 1 4. 3. 2 5 Layout and post-simulation†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦ 3 5. 1 5. 2 5. 3 Layout of SAFF and post-simulation †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. 33 Layout of parallel TDC and post-simulation †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦ 35 Comparison and analysis †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã ¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. 38 6 7 8 Conclusion †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦ 0 Future work †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. 41 Reference †¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦.. 42 iii LIST OF FIGURES Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 Figure 20 Figure 21 Figure 22 Figure 23Figure 24 Figure 25 Figure 26 Figure 27 Figure 28 Figure 29 Figure 30 Figure 31 Figure 32 Figure 33 Figure 34 Figure 35 Figure 36 Figure 37 Figure 38 Figure 39 Figure 40 Figure 41 Figure 42 Figure 43 Figure 44 Figure 45 iv Effect of LO phase noise in transmitter Block diagram of the phase-domain ADPLL frequency synthesizer Retiming of the reference clock signal (FREF) Operating principle of time-to-digital converter Buffer delay line TDC Inverter delay line TDC Vernier delay line TDC Gated ring oscillator TDC Test bench for measuring rising/falling time of input of TDC Input and output of inverter Diagram of Vernier delay line TDC Timing of the interfaces of Vernier TDC Diagram of parallel TDC Timing of the interfaces o f parallel TDC Symmetric SAFF Schematic of SAFF Schematic of Sense Amplifier Schematic of symmetric SR latch Test bench of SAFF Normal Sampling Case Extreme case of sampling for setup time simulation Extreme case of sampling for hold time simulation Sampling window simulation Current starved delay element Schematic of Matched delay cell Schematic of delay cell 1 Schematic of delay cell 2 Schematic of Vernier delay line TDC Input of Vernier TDC (stop – start) = 0ps Input of Vernier TDC (stop – start) = 20ps Vernier TDC transfer function Vernier TDC linearity Monte Carlo simulation of the resolution for Vernier delay line TDC Delay cell in Parallel TDC Delay time Vs width of transistor T5 Schematic of Parallel TDC Input of parallel TDC (stop – start) = 0ps Input of parallel TDC (stop – start) = 20ps Parallel TDC transfer function Parallel TDC linearity Floor Plan of SAFF Layout of SAFF Post-simulation of sampling window Floor plan of Clock distribution Layo ut of parallel TDC Figure 46 Figure 47 Figure 48 Figure 49 Input of parallel TDC after layout (stop – start) = 0ps Input of parallel TDC after layout (stop – start) = 30ps Parallel TDC transfer function after layout Parallel TDC linearity after layout LIST OF TABLES Table 1 Table 2 Performance comparison between Vernier TDC and parallel TDC Comparison to previous work v 1.Introduction All digital phase locked loop (ADPLL) is employed as frequency synthesizer in radio frequency circuits to create a stable yet tunable local oscillator for transmitters and receivers due to its low power consumption and high integration level. It accepts some frequency reference (FREF) input signal of a very stable frequency of and then generates frequency output as commanded by frequency command word (FCW). The desired frequency of output signal is an FCW multiple of the reference frequency. For an ideal oscillator operating at all power is concentrated around , but the spectrum spreads i nto nearby frequencies in practical situation.This spreading is referred as phase noise which can cause interference in adjacent bands in transmitters and reduce selectivity in receivers [1]. Fig. 1. Effect of LO phase noise in transmitter [1] For example, shown as Fig. 1, when a noiseless receiver must detect a weak desired signal at frequency in the presence of a powerful nearby transmitter generating at frequency with substantial phase noise, the desired signal will be corrupted by phase noise tails of transmitter. Thus the modern radio communication systems require strict specifications about phase noise of synthesizers. In the ADPLL, the time to digital converter (TDC) serves as the phase frequency detector (PFD) meanwhile the digitally controlled Oscillator (DCO) replaces the VCO.The core module is DCO which deliberately avoids analog tuning voltage controls. The DCO is similar to a flip flop whose internal is analog but the analog nature does not propagate beyond the boundari es. Compared to the analog PLL, the loop filter can be implemented in a fully digital manner which will save a large amount of area and maintain low power consumption. 1 Fig. 2. Block diagram of the phase-domain ADPLL frequency synthesizer [2] Fig. 2 shows a type II ADPLL which includes two poles at zero frequency. It has better filtering capabilities of oscillator noise compared to type I ADPLL, leading to improvements in the overall phase noise performance. The ariable phase signal is determined by counting the number of rising clock transitions of the DCO oscillator clock. The reference phase signal is obtained by accumulating the Frequency Command Word (FCW) with every rising edge of the retimed Frequency Reference (FREF) clock. The sampled variable phase is subtracted from the reference phase in a synchronous arithmetic phase detector which is defined by = + ? [k] [2]. Fig. 3. Retiming of the reference clock signal (FREF) [3] 2 There are two asynchronous clock domains, FREF and CKV, and it is difficult to compare the two digital phase values physically at different time instances without facing the metastability problem.During frequency acquisition, their edge relationship is not known, and during phase lock, the edges will exhibit rotation if the fractional FCW is nonzero [1]. Therefore, it is imperative that the digital-word phase comparison should be performed in the same clock domain. This is achieved by retiming process which is performed by oversampling the FREF clock with CKV for synchronization purpose (fig. 3). The retimed clock, CKR is used to synchronize the internal ADPLL operations. However, the retiming process generates a fractional phase error in CKV cycles which is estimated by TDC [3]. The DCO produces phase noise at high frequency, while the TDC determines the in band noise floor [4].The noise contribution of TDC within the loop bandwidth at output of ADPLL is where denotes the delay time of a delay cell in the TDC chain, is the period of RF output and is the frequency of the reference clock [1]. The equation above indicates that a smaller leads to smaller quantization noise from TDC. As a result, the effort is devoted to achieve high resolution TDC in order to obtain low phase noise of ADPLL. Fig. 4. Operating principle of time-to-digital converter [5] Fig. 4 illustrates the principle of time-to-digital converter based on digital delay line. The start signal is delayed by delay elements and sampled by the arrival of the rising edge of stop signal.The sampling process which can be implemented by flip-flops freezes the state of delay line as the stop signal occurs. The outputs of flip-flop will be high value if the start signal passes the delay stages and the sampling process will generate low value if the delay stages have not been passed by start signal. As a result, the position of high to low transition in this thermometer code indicates how far the start signal can be propagated in the interval spanned by star t and stop signal. 3 2. State of art 2. 1 Buffer delay line TDC Fig. 5. Buffer delay line TDC [5] The start signal ripples along the buffer chain and flip-flops are connected to the outputs of buffers. On the arrival of stop signal the state of delay line is sampled by flip-flops.One of the obvious advantages of this TDC is that it can be implemented fully digital. Thus it is simple and compact. However, the resolution is relatively low since it is the delay of one buffer. 2. 2 Inverter delay line TDC Fig. 6. Inverter delay line TDC [5] The resolution in this TDC is the delay of one inverter which is doubled compared to buffers delay chain. In this case, the length of measurement intervals is not indicated by the position of high to low transition but by a phase change of the alternation of high to low sequence. Consequently, the rise and fall delay of inverter should be made equal which requires highly 4 match of the process.In addition, the resolution is still limited by technolog y and therefore not high enough in our application of ADPLL. 2. 3 Vernier TDC Fig. 7. Vernier delay line TDC [6] Vernier delay line TDC is capable of measuring time interval with sub-gate resolution. It consists of two delay lines which delay both start signal and stop signal. The delay in the first line is slightly larger than the delay in the second line. During the measurement, the start signal propagates along the first line and the stop signal occurs later. It seems like the stop signal is chasing start signal. In each stage, it catches up by = Delay1- Delay2 Therefore the resolution is dependent on the difference of two delay stages instead of one delay element.Although the Vernier delay line TDC improves the resolution effectively, the area and power consumption is increased dramatically as the dynamic range becomes larger due to that each stage costs two buffers and one flip-flop. Besides, the conversion time will be increased and in a result it might be not feasible to work in a system. 5 2. 4 Gated ring oscillator (GRO) TDC Fig. 8. Gated ring oscillator TDC [6] The GRO TDC could achieve large dynamic range with small number of delay elements. It measures the number of delay element transitions during measurement interval. By preserving the oscillator state at the end of the measurement interval [k? ], the quantization error [k? 1], from that measurement is also preserved. In fact, when the following measurement of [k? 1] is initiated, the previous quantization error is carried over as [k] = [k? 1]. This results in first-order noise shaping of the quantization error in the frequency domain. Apart from the quantization noise, according to the well-known barrel shift algorithm for dynamic element matching, GRO TDC structure realizes first order shaping of mismatch error [6]. Thus, we can expect that this architecture ideally achieve high resolution without calibration even in the presence of large mismatch. 6 3 System level design 3. 1 GoalThe proposed TDC is designed to work with a 5GHz DCO and a 20MHz reference input while the circuit is fabricated in 65nm IBM CMOS technology; the supply voltage is 1. 2V and development environment is Cadence 6. 1. 3. Fig. 9. Test bench for measuring rising/falling time of input of TDC In order to find out the rising/falling time of the input signal for TDC, the 5GHz sine wave signal which is the same as the output of DCO in ADPLL is put through the inverter with the smallest size and the rising/falling time of the output of inverter is measured (Fig. 9) . 7 Fig. 10. Input and output of inverter Rising/falling time = 16. 58ps. This value is applied to model the practical case of input signals for TDC.The purpose for putting the sinusoid signal generated from DCO passing through the smallest inverter is to model the worst case for TDC with weakest driving ability. As the system level simulation result of ADPLL presents, the dynamic range of TDC is 20ps. The converter resolution is required to be around 2ps meanwhile the power consumption should be kept as low as possible. Since in the application of this ADPLL, sub-gate resolution and small dynamic range are targeted, two kinds of topologies of TDC are proposed. One is Vernier delay line TDC and the other one is parallel TDC. The comparison of these two architectures is concluded and both of them are designed on schematic level. 8 3. 2 Vernier delay line TDCStart Matched delay cell1 EN EN_ Delay1 Delay1 Delay1 Start_ Matched delay cell1 D Q D_ CLK Delay1 D Q0 D_ CLK Delay1 Delay1 D Q26 D_ CLK Stop Fig. 11. Diagram of Vernier delay line TDC 200ps Matched delay cell2 Delay2 Delay2 Delay2 start 20ps stop enable Valid output 2ns TDC_output Fig. 12. Timing of the interfaces of Vernier TDC As the description about Vernier TDC before, the start signal and stop signal are propagated by two delay line with small delay difference each stage respectively. The clock gating technology controlled by enable signal is used to realize low p ower dissipation. The timing relationship of interfaces is described in Fig. 2 which indicates that enable signal should be set to high value half 9 cycle of start signal ahead of the stop rising edge and the conversion time is about 2ns. The delay time of each stage in TDC is about 60ps to 70ps and 27 stages are design to cover the whole dynamic range so that the conservative estimation of conversion time of TDC would be no more than 2ns. The next stage of TDC in ADPLL should sample the output when it is stable. Since the period of FREF is 50ns which means that the instance of measurement occur every 50ns, it is reasonable to adopt the method of serial conversion and prepare the valid output data after 2ns delay. 3. 3Parallel TDC Start Current Staved delay cell EN EN_ Start_ Current Starved delay cell D Q0 D_ CLK Stop Fig. 13. Diagram of parallel TDC Delay1 Delay2 Delay12 D Q1 D_ CLK D Q11 D_ CLK 10 200ps 20ps start stop enable Valid output 420ps TDC_output Fig. 14. Timing of the i nterfaces of parallel TDC Configuring the gates not in a chain but in parallel generates TDC depicted in Fig. 13. The start signal applied to all delay elements in parallel. On the rising of stop signal the outputs of all delay elements are sampled at the same time. Instead of propagating the differential start signal, stop signal is delayed to avoid differential mismatch problem.The delay cells connected to stop signal are sized for delays = 0+? ?N =? . The time difference between the delayed stop signal is quantized with a resolution The conversion results are available immediately after the rising of stop signal. 3. 4 Performance comparison Parallel TDC Parallel delay elements with gradually increasing propagation delays are simultaneously sampled on the arrival of stop signal. No loop structure feasible Sub-gate resolution Conversion time independent from resolution Susceptible to variations Not feasible to high dynamic range Careful layout design Vernier TDC Principle Start and stop signals propagate along two delay lines with slightly different delays.Loop structure Pros Loop structure possible Sub-gate resolution Modular structure High dynamic range possible with loop structure Differential delay lines Conversion time depends on measurement interval and resolution Cons Table1. Performance comparison between Vernier TDC and parallel TDC 11 4 Schematic design and simulation 4. 1 Sense Amplifier Based Flip-Flop Flip-Flops are critical to the performance of Time to Digital Converter due to the tight timing constraints and low power requirements. Metastability is a physical phenomenon that limits the performance of comparators and digital sampling elements, such as latches and flip-flops. It recognizes that it akes a nonzero amount of time from the start of a sampling event to determine the input level or state [15]. This resolution time gets exponentially larger if the input state change gets close to the sampling event. In the limit, if the input changes a t exactly the same time as the sampling event, it might theoretically take an infinite amount of time to resolve. During this time, the output can dwell in an illegal digital state somewhere between zero and one. However, this flip flop is supposed to be reused in ADPLL so that the metastable condition of the retimed reference clock CKR is not acceptable. One reason is that the metastability of any clock could introduce glitches and double clocking in the digital logic circuitry being driven.The other reason is that it is quite likely that within a certain metastability window between FREF and CKV, the clock to Q delay of the flip flop would have the potential to make CKR span multiple DCO clock periods. This amount of uncertainty is not acceptable for proper system operation [4]. For the application of TDC, due to that the metastability sampling window should be no larger than the high resolution to avoid bubbles in TDC code [7], sensed amplifier based flip-flop (SAFF) is chosen. 1 2 VDD MP1 MP2 MP3 MP4 MN3 VDD MN4 D MN1 MN5 MN2 D_ CLK MN6 Pulse Generator Symmetrical SR latch S_ S R VDD R_ MP7 MP8 MP5 MP6 MP9 Q MP10 Q_ MN9 MN10 MN7 MN11 MN12 MN8 Fig. 15. Symmetric SAFF The SAFF shown as Fig. 5 consists of sense amplifier in the first stage and SR latch in the second stage. The amplifier senses complementary differential inputs and produces monotonous transitions from high to low logic level on one of the outputs following the leading clock edge. The SR latch captures each transition and holds the state until the next leading clock arrives [8]. When CLK is low, S_ and R_ are charged to high level through MP1 and MP4 meanwhile MN6 is closed. If D is high, S_ will be discharged through MN3, MN1 and MN6 which is opened by clock leading edges. Accordingly, R_ is hold to high level and Q is high in this case. The additional transistor MN5 is used to provide the discharging patch to ground. For example, when 13 ata is changed as CLK is high which means D is low and D _ is high at this time, S_ would be charging to high level if there is no MN5. However, S_ could be discharged through MN3, MN5, MN2 and MN6 since MN5 provides another path to ground. Although SR latch is able to lock the state of outputs of sense amplifier, MN5 prevents potential charging caused by leakage current even after the input data is changed and therefore guarantee the stable outputs of flip-flop. The SR latch, as the output stage, is kind of symmetric topology with equivalent pull-up and pulldown transistors network. Q+ = S + R_ ·Q Q_+ = R + S_ ·Q_ In the equations above, Q represents a current sate and Q+ represents a future state after the transition of clock.Thus this circuit has equal delays of outputs and provides identical resolution of the rising and falling meta-stability of their input data. In addition, the data input capacitive loading is only one NMOS transistor and the interconnect capacitance parasitic is minimized. 4. 1. 1 Schematic design The basic pri nciples of the SAFF design are that the size of the input transistors should be small enough to minimize the load effect of SAFF and large enough to ensure the speed of it. The PMOS and NMOS networks should be matched and the sizes of transistors are adjusted to obtain equal delay of differential outputs. Fig. 16. Schematic of SAFF 14 Fig. 17. Schematic of Sense Amplifier Fig. 18. Schematic of symmetric SR latch 15 4. 1. 2 Sampling window simulation Fig. 19.Test bench of SAFF The ideal switch is used to initialize the output signal Q otherwise Q will be floating at the beginning of simulation which would result in unpredictable rising or falling edge at the beginning therefore make it difficult to measure a fixed number of signal transition edge. In the practical case, the initial value of inputs of flip flop is either zero or one. The simulation is performed by tuning the delay time of CLK in order to change the time interval between CLK and D/D_. There are several cases simulated to verify the timing constraints of SAFF including setup timing, hold timing and sample window. 1. Normal sampling 16 Fig. 20. Normal Sampling Case Data D changes from zero to one and then is sampled after it is stable for a while. The crossing point of Q and Q_ is around 600mV which means there are equal delay of clock to Q and clock to Q_ due to the symmetric topology of SAFF. 2.Setup time simulation Setup time is the minimum time prior to triggering edge of the clock pulse up to which the data should be kept stable at flip flop input so that data could be properly sampled. This is due to the input capacitance present at the input. It takes some time to charge to the particular logic level at the input. During the simulation, the input data is changing from low to high and high value is supposed to be sampled. Sweep the position of CLK to find out when SAFF cannot capture the correct data. 17 Fig. 21. Extreme case of sampling for setup time simulation The clock to Q delay is incre asing exponentially when input data is approaching the clock triggering edge.When the data comes later than clock edge for 15ps, the clock to Q delay is up to about 280ps shown in Fig. 21. If the data comes even later than this, the output of flip flop will enter into metastable state or will never output high value. 3. Hold time simulation Hold time is the minimum time after the clock edge up to which the data should be kept stable in order to trigger the flip flop at right voltage level. This is the time taken for the various switching elements to transit from saturation to cut off and vice versa. During the simulation, the input data is changing from high to low and high value is supposed to be sampled. Sweep the position of CLK to find out when SAFF cannot capture the correct data. 18 Fig. 22.Extreme case of sampling for hold time simulation The clock to Q delay is increasing exponentially if transition of input data from one to zero happens close to the clock edge. As long as t he data could keep stable long enough the flip flop is capable of recognizing it during limit time interval. The hold timing constraint is that data should be stable after the clock rising at least 16ps (Fig. 22) to guarantee flip-flop could sample the right value otherwise the flip flop will enter into illegal state or never output high value. 4. Sampling window 19 2. 9 2. 8 2. 7 2. 6 x 10 -10 Tclk-Q 2. 5 setup time 2. 4 2. 3 2. 2 2. 1 2 -0. 5 hold time 0 0. 5 1 1. 5 2 Tdata-clk 2. 5 3 3. 5 x 10 4 -11 Fig. 23. Sampling window simulationSampling window is defined as the time interval in which the flip-flop samples the data value. During the interval any change of data is prohibited in order to ensure robust and reliable operation [8]. The flip-flop delay increases as the signal approaches the point of setup and hold time violation until the flip-flop fails to capture the correct data [9] which is displayed in Fig. 23. Metastability is modeled in critical flip-flops by continuous ins pection of the timing relationship between the data input and clock pins and producing an unknown output on the data output pin if the delay to clock skew falls within the forbidden metastable window. Referring to Fig. 3, the metastable window is defined as an x-axis region such that the clock to Q delay on the y-axis is longer by a certain amount than the nominal clock to Q delay. For example, if the nominal clock to Q delay is 200ps when the data to clock timing is far from critical, the metastability window would be 15ps if one can tolerate clock to Q delay increase by 20ps. If one can tolerate a higher clock to Q delay increase of 30ps, the metastable window would drop to 6 ps. A question could be asked as to how far this window can extend. The limitation lies in the fact that for a tight data to clock skew, the noise or other statistical uncertainty, such as jitter, could arbitrarily resolve the output such that the input data is missed.Therefore, for a conventional definition of setup time, not only must the output be free of any metastable condition, but the input data have to be captured correctly. For this reason, the setup and hold times are conservatively defined in standard-cell libraries for an output delay increase of 10 or 20% over nominal. The specific nature of TDC vector capturing does not require this restrictive constraint. Here, any output-level resolution is satisfactory for proper operation as long as it is not metastable at the time of capture, and consequently, 20 the metastable window could be made arbitrarily small [1]. This SAFF demonstrates very narrow sampling window less than 1ps according to the simulation results. 4. 2Vernier delay line TDC There are several components in Vernier delay line TDC including inverter, SAFF, matched delay cell, delay cell 1 and delay cell 2 in which matched delay cell has the same circuit topology with other two delay cells except that it has enable control pins. 4. 2. 1 Delay cells There are severa l methods to implement delay elements. The most popular three methods for designing variable delay cells are shunt capacitor technique, current starved technique and variable transistor technique [10]. In this thesis project, current starved delay element is employed because of its simple structure and relatively wide delay range of regulation.Vdd VBP M4 M2 M6 Vdd in C M1 M5 out VBN M3 Fig. 24. Current starved delay element As can be seen from the Fig. 24, there are two inverters between input and output of this circuit. The charging and discharging currents of the output capacitance of the first inverter, composed of M1and M2, are controlled by the transistors M3 and M4. Charging and discharging currents depend on the bias voltage of M3 and M4 respectively. In this delay element, both rising and 21 falling edges of input signal can be controlled. By increasing/decreasing the effective on resistance of controlling transistor M3 and M4, the circuit delay can be increased /decreased.F ig. 25. Schematic of Matched delay cell As the enable signal is set to high level, the input signal will pass through this delay cell. The enable signal should be set to high level before the active edge of input signal comes. The differential start signal and stop signal passed through this delay cell to produce matched rising/falling edge signal for the next stage in TDC. With respect to design of the size of transistors, the input transistors of the delay cell should be relatively large to shield the load effect of SAFF meanwhile allow T5 to control the changing and discharging current through the capacitors of the first stage of inverter.The second stage of inverter should have enough driving ability for 5GHz input signals and therefore the sizes are specified large enough to withdraw sufficient current from power supply for transition. Due to that the differential signals are delayed, the delay cell is also required to have matched PMOS and NMOS networks to achieve equal delay time for rising or falling input signals. 22 Fig. 26. Schematic of delay cell 1 Fig. 27. Schematic of delay cell 2 23 The only difference between these two delay cells above is the size of transistor T5. The W/L ratio of T5 in delay cell 2 is a bit larger than delay cell 2 makes the delay of delay cell 2 is slightly shorter than delay cell 1. These two delay cells constitute two delay lines for Vernier TDC. Fig. 28.Schematic of Vernier delay line TDC This Vernier TDC includes 27 stages of delay cells for the reason that it should cover the dynamic range of 20ps and the additional offset value introduced by the setup timing of SAFF. The first dumpy stage of delay cell is used to match the differential input signals for the following delay lines so that the input signals for each stage are characterized with the same rising or falling time. As a result, the delay difference between each delay pair for start and stop signal is only dependent on the different size of transistors in the current starved delay cell. 24 4. 2. 2 Simulation results The input of Vernier TDC, the delay difference between the start and stop signal, is swept from 0 to 20ps.The resolution and linearity are calculated and analyzed by conversion results from TDC. Fig. 29. Input of Vernier TDC (stop – start) = 0ps Fig. 30. Input of Vernier TDC (stop – start) = 20ps 25 The offset value of this TDC is 8 observed from Fig. 29. The result shown in Fig. 30 indicates that the start signal has passed through 22 stages of delay cells as the input is 20ps. Resolution = (20ps – 0ps)/ (22 – 8) = 1. 43ps 25 20 Output of Vernier TDC (ps) 15 10 5 0 0 2 4 6 8 10 12 14 Input of Vernier TDC (ps) 16 18 20 Fig. 31. Vernier TDC transfer function 0. 6 0. 4 0. 2 DNL and INL [LSB] 0 -0. 2 -0. 4 -0. 6 -0. 8 -1 INL DNL 0 2 4 6 8 10 12 Input of Vernier TDC 14 16 18 20 Fig. 32. Vernier TDC linearity 26The Differential Non Linearity (DNL) is the deviation in the difference between two successiv e threshold points from 1LSB. Integral Non Linearity (INL) is the deviation of the actual output. Both of them are calculated and reported in Fig. 32. The maximum DNL is +0. 4LSB while the maximum INL is -0. 89LSB. The process (skew) parameter files in the model directory contain the definition of the statistical distributions that represent the main process variations for the technology. This gives designers the capability of testing their designs under many different process variations to ensure that their circuits perform as desired throughout the entire range of process specifications. This is a Monte Carlo approach to the checking of designs.While being the most accurate test, it can also be time consuming to run enough simulations to obtain a valid statistical sample. Fig. 33. Monte Carlo simulation of the resolution for Vernier delay line TDC When running Monte Carlo to include FET mismatch, BOTH the Spectre mismatch and process vary statements are active. This will turn on b oth process and mismatch variations. Spectre provides the unique capability of running process variations independent of mismatch variations. This capability is not supported for this release. The average resolution calculated by averaging the delay difference between two delay lines is around 1. 66ps. The average power over one period is 148. 1E-6 W.The maximum power consumption is about 3. 6mW and the conversion time is around 2ns which is in accordance with the interfacing time estimation in system level design. Since the enable signal closed the TDC after the conversion is completed, the start signal with high frequency is prohibited to propagate so as to eliminate the unnecessary transition of delay cells and in a result saving the power dissipation. 27 4. 3 4. 3. 1 Parallel TDC Delay cells In order to design a serial of delay cells with the equal difference of delay time used in parallel TDC, the size of the transistor in a current starved structure is swept. Fig. 34. Delay ce ll in Parallel TDC 28Fig. 35. Delay time Vs width of transistor T5 Unlike Vernier TDC, only stop signal is delayed by various delay cells in parallel TDC. Thus the control of rising edge required, and then the size of transistor T5 is adjusted. As can be seen from Fig. 34, the size of transistors M1, M2, M4 and M5 is basically determined by the load capacitance which refers to the CLK pin of SAFF in this situation. Transistor T5 should be much smaller than M2 so that the discharging current could be controlled by T5. As the size of T5 increases, the delay time becomes smaller which means the delay cell is faster. According to the parameter analysis result in Fig. 5, the size of T5 can be determined by selecting the size corresponding to the delay time with 2ps difference for a serial delay cells. Fig. 36. Schematic of Parallel TDC 29 As the analysis in system level design, the delay cells are sized for delays = 0 + ? ?N. The single stop signal is delayed in parallel TDC, therefore t he matched delay cell connected to differential start signal is used to cancel the 0 and offset value. 4. 3. 2 Simulation results Similarly to Vernier TDC simulation, the input of parallel TDC, the delay difference between the start and stop signal, is swept from 0 to 20ps. The resolution and linearity are calculated and analyzed by conversion results from TDC. Fig. 37.Input of parallel TDC (stop – start) = 0ps 30 Fig. 38. Input of parallel TDC (stop – start) = 20ps The offset value of this TDC is 1 observed from Fig. 37. The result shown in Fig. 38 indicates that the start signal has passed through 11 stages of delay cells as the input is 20ps. Resolution = (20ps – 0ps)/ (11 – 1) = 2ps. 20 18 16 Output of parallel TDC (ps) 14 12 10 8 6 4 2 0 0 2 4 6 8 10 12 14 Input of parallel TDC (ps) 16 18 20 Fig. 39. Parallel TDC transfer function 31 1 INL DNL DNL and INL [LSB] 0. 5 0 -0. 5 0 2 4 6 8 10 12 Input of parallel TDC 14 16 18 20 Fig. 40. Parallel TDC linea rity DNL and INL are calculated and reported in Fig. 40. The maximum DNL is +0. LSB while the maximum INL is 1LSB. The average power over one period is 87. 33E-6 W which is much smaller than Vernier TDC. The reason is that the clock gating technology controlled by enable signal eliminates the redundant transition of delay cells. As the system level design indicates, the parallel TDC only works for 420ps each period of stop signal because that the conversion is completed instantly due to the intrinsic characteristic of parallel TDC and therefore there is no power consumption during the rest time. Although the peak power consumption is approximately equivalent to Vernier TDC, the average power dissipation is decreased dramatically. 32 Layout and post-simulation 5. 1 Layout of SAFF and post-simulation For the layout of radio frequency circuit the interconnection parasitic will be a critical problem. In an audio application for instance parasitic will probably be a minor concern. Howeve r, the operation frequency of this circuit is 5GHz which means that the interconnection parasitic will influence the performance of circuit dramatically. To minimize this influence, we could move interconnections to higher metals and make the metals carry current rather than poly. Besides, the floor plan should be as compact as possible to optimize the parasitic and impedance of interconnections. GND T0Symmetric SR Latch T15 T14 T13 T8 T9 T5 T3 Q_ T1 T12 T10 T11 T7 Q T6 T4 T2 VDD T0 T2 T4 T3 T5 T9 T1 D T6 T7 D_ CLK T8 CLK GND Sensed Amplifier Fig. 41. Floor Plan of SAFF 33 There are several steps for floor plan. First step is to examine the size of transistors and split transistor size in a number of layout oriented fingers. Then identify the transistors than can be placed on the same stack according to the principles of using almost the same number of fingers per stack and put the transistors with common drain or source together. In the floor plan shown in Fig. 41, power line VDD i s reused by SR latch and sensed amplifier to make the connections compact.Fig. 42. Layout of SAFF 34 In the development environment of Cadence 6. 1. 3, Calibre is used for DRC and Assura is used to do LVS check and RCX. Post-simulation is then performed with av_extracted view. Fig. 43. Post-simulation of sampling window Compared to Fig. 23, Fig. 43 illustrates that the timing constraint point moved from 16ps to 29ps which will affect the offset value of TDC. In addition, the delay time from clock leading edge to output Q is increased. However, this SAFF after layout can be employed to avoid meta-stability effectively due to that the sampling window is still less than 1ps. 5. 2 Layout of parallel TDC and post-simulationIn this TDC system, the clock distribution network formed as a tree distributes the signal to all the delay cells. To reduce the clock uncertainty, the network requires highly matched topology showed as Fig. 44 below. 35 Clock Fig. 44. Floor plan of Clock distribution This kind of topology guarantees the equal delay from the common point clock to each element. Fig. 45. Layout of parallel TDC After DRC and LVS, the RC net list is extracted to do post-simulation. The input of parallel TDC after layout, the delay difference between the start and stop signal, is swept from 0 to 30ps. The resolution and linearity are calculated and analyzed by conversion results from TDC. Fig. 46.Input of parallel TDC after layout (stop – start) = 0ps 36 Fig. 47. Input of parallel TDC after layout (stop – start) = 30ps The offset value of this implemented TDC is 0 observed from Fig. 46. The result shown in Fig. 47 indicates that the start signal has passed through 10 stages of delay cells as the input is 30ps. Resolution = (30ps – 0ps)/ (10 – 0) = 3ps. 35 30 Output of parallel TDC after layout (ps) 25 20 15 10 5 0 0 5 10 15 20 Input of parallel TDC after layout (ps) 25 30 Fig. 48. Parallel TDC transfer function after layout 37 0. 5 0. 4 0. 3 DNL and INL after layout [LSB] 0. 2 0. 1 0 -0. 1 -0. 2 -0. 3 -0. 4 -0. 5 INL DNL 0 5 10 15 20 Input of parallel TDC (ps) 25 30 Fig. 49.Parallel TDC linearity after layout DNL and INL are calculated and reported in Fig. 49. The maximum DNL is 0. 33LSB while the maximum INL is 0. 5LSB. The average power over one period is 442. 1E-6 W. The maxim total current is about 3. 24mA. The peak power consumption is almost the same as the TDC before layout, but there are obvious ripples even the TDC is disabled due to that the parasitic capacitors increase the time for charging and discharging. 5. 3 Comparison and analysis Technique Parallel 2-level DL parallel Pseudo-diff DL VernierGRO CMOS [ µm] 0. 065 0. 35 0. 13 0. 09 0. 09 Supply [V] 1. 2 3 1. 2 1. 3 1. 2 Power [mW] 3. 89 50 2. 5 6. 9 4. 32 Resolution [ps] 3 24 12 17 6. 4 INL/DNL 0. 5/0. 3 -1. 5/0. 55 -1. 15/1 0. 7/0. 7 – Work This [12] [3] [7] [13] Table2. Comparison to previous work Table2 compares the proposed TDC to prior pub lished work in CMOS technology. This TDC features the fastest resolution with the best linearity. The power consumption is not directly comparable because the results from the other works are corresponding to different input range. However, it still indicates that this TDC consumes very low power due to that the start signal 38 only passes two buffers and the stop signal with low frequency is delayed. The TDC error has several components: quantization, linearity and randomness due to thermal effects.As can be seen from table5, the implemented TDC achieves medium linearity which can be improved if the layout is enhanced from floor plan considering the parasitic effects. With respect to quantization noise, the total noise power generated from this kind of TDC is spread uniformly over the span from dc to the Nyquist frequency without modulation. As a result, the proposed TDC contributes the lowest noise floor due to high resolution. = =3ps, , = 20MHz, we obtain = -104. 3 dBc/Hz. Banerj ee’s figure of merit (BFM) [14], being a 1-Hz normalized phase noise floor, is defined as BFM = where is a sampling frequency of the phase comparison and N= is the frequency division ratio of a PLL.It is used to compare the phase performance of PLLs with different reference frequencies and division ratios. In this TDC based ADPLL, BFM = -225. 3dB. Even though state-of-the-art conventional PLLs implemented in a SiGe process can outperform the ADPLL presented here in the in band phase noise, -213 dB in reference and -218 dB in reference, the worst case BFM of -205 dB appears adequate even for GSM applications, since there are no other significant phase-noise contributions as in the conventional PLLs [4]. However, the Gated Ring Oscillator TDC is able to push most of the noise to high frequency region which is then filtered by the loop filter in ADPLL through holding oscillation node state between measurements.The obvious drawback of this TDC is that the dynamic range is relativ ely small which will limit the application of it. Parallel TDC is not feasible to compose the loop structure so that the area and power dissipation will be increased dramatically if larger dynamic range is required. But the Vernier TDC designed in this thesis can be used in the loop structure for large dynamic range. 39 6 Conclusion In this thesis, two kinds of Time to Digital Converters are designed with Vernier and parallel structure on schematic level respectively. The performance of these two TDCs are concluded and compared. In the Vernier TDC, only two delay cells are designed and then reused to constitute two delay lines with slightly different delay time.This architecture is easy to implement and reduces the mismatch with delay cells. But the conversion time dependent on resolution and measurement interval time is relatively long since the signals are propagating along the delay cells in serial. On the other hand, in parallel TDC, the process of conversion is completed instan taneously due to that the signals are passing through the delay cells and then captured in parallel. Thus it has lower average power dissipation over one period. However, a set of delay cells are designed which obviously introduce nonlinearities. To minimize the mismatch problem, the single stop signal is delayed instead of two input signals for avoiding the differential mismatch situation.To sum up, both of the TDCs achieve sub-gate resolution which is able to meet the application requirements and Vernier TDC has higher resolution and better linearity but longer conversion time and larger power consumption compared to parallel TDC according to the simulation results. The parallel TDC is chosen to be implemented on layout. Comparing the results from schematic simulation and post-simulation, the performance is decreased on resolution, linearity and power consumption after layout. The major reason for this phenomenon is the parasitic capacitance of transistors and real wires which is a significant factor to affect the final properties in high frequency circuits.In the stage of schematic design, the sizes of transistors are not fully considered and results in difficulties on floor plan of layout. Specifically, the transistors are rather difficult to split into the same fingers per stack and therefore the floor plan is not compact enough to minimize the interconnections. Besides, the parasitic capacitance should have been emulated on schematic simulation in order to predict the effect after layout otherwise it would be very time consuming if the schematic design is modified after layout. In addition, the size of transistors is very small which makes them comparable to wire parasitic effects. Although small transistors are with smaller parasitic capacitance and less power consumption, they will more sensitive to layout mismatch.The function of the TDCs designed and implemented in the thesis is guaranteed for the application but the performance needs to be improved. The layout turns out to be an essential stage for the final characteristics of the circuits. With a more thoughtful design flow and sophisticated consideration for mismatch, the circuits after layout could maintain the performance as schematic level. 40 7 Future work There is plenty of more work to be done to improve the performance of TDC. Due to that the TDC is essential to the aggressive goal of phase noise from all digital PLL, other kinds of architectures of it are worth to try for the required resolution and dynamic range. Since the performance of circuit after layout is not identical with schematic, the size of transistors could be modified for layout oriented. To reduce the parasitic effects, layout should be improved from a better floor plan. Vernier TDC with higher resolution and better linearity could be implemented on layout which can tolerate first order PVT variation if two delay chains are well matched [11]. Although the Vernier TDC and parallel TDC achieve high reso lution, they have very low efficiency when measuring large time intervals, which requires extra hardware and power consumption. To overcome this limitation, a Vernier Ring TDC has been proposed recently.Unlike the conventional Vernier TDC, this novel TDC places the Vernier delay cells in a ring format such that the delay chains can be reused for measuring large time intervals. Digital logic monitors the number of laps the signals propagate along the rings. Arbiters are used to record the location where the lag signal catches up with the lead signal. The reuse of Vernier delay cells in a ring configuration achieves fine resolution and large detectable range simultaneously with small area and low power consumption [11]. This architecture of Vernier Ring TDC combines the Vernier delay lines and GRO topology is worth to implement for wide application. ? ? 41 8 [1] [2] [3] [4] [5] [6] [7]