Positive Feedback Amplifier Essays

Positive Feedback Amplifier Essays Positive Feedback Amplifier Essay Positive Feedback Amplifier Essay FEEDBACK AMPLIFIER FEED BACK: The process of applying a fraction of output energy of some device back to the input known as feedback. FEEDBACK AMPLIFIER: The amplifier using feed back process is called feedback amplifier. TYPES OF FEEDBACK AMPLIFIER: There are two types of feedback amplifier: a)Positive feedback amplifier b)Negative feedback amplifier POSITIVE FEEDBACK AMPLIFIER: >The amplifier in which feedback energy is applied in the same polarity or in same phase is called as positive feedback amplifier. increases the voltage gain of mplifier. his distortion is more. has increased instability. seldom used as an amplifier. Mostly used in oscillator. NEGATIVE FEEDBACK AMPLIFIER: >The amplifier in which feedback energy is applied in the opposite polarity or out of phase with input is called negative feedback amplifier. decreases the voltage gain. this distortion is less. is more stable. is mostly used as an amplifier. PRINCIPLE OF NEGATIVE FEEDBACK AMPLIFIER: >Block diagram of negative feedback amplifier: >A=Voltage gain without feedback. Af=Aoltage gain with feedback. Vi=lnput signal to be amplified. Vo= Output signal of amplifier Vd=Actual input signal to the amplifier. Vf= Feedback signal applied to input side. m=feedback fraction >From block diagram it is clear that, m=VfNo i. e. Vf=mVo Again A=VoNd i. e. i. e. Vo=AVi-AmVo i. e. Vo+AmVo=AVl i. e. Af=l /(! +mA) OF NEGATIVE FEEDBACK AMPLIFIER: 1 -Resultant gain is independent of transistor parameters or supply voltage fluctuation. Hence gain is stable. 2-lt reduces non-linear distortion by a factor (1 +mA). 3-lt improves frequency response. 4-lt increases circuit stability. lt increases input impedance decreases output impedance. INPUT IMPEDANCE OUTPUT IMPEDANCE WITH FEEDBACK: >Figure shows the block diagram: >Given that: Zi=input impedance without feedback=Vd/i1 Zif=lnput impedance with feedback†Wil Zo=Output impedance without feedback Zof=output impedance with feedback il †input current >From block diagram it is clear that Now Or VI/ It is clear that input impedance with feedback increases by a factor (1 +mA). Si milarly, it can be derived that output impedance without feedback decreases by a factor 1 +mA). . e. +mA) EMITTER FOLLOWER: *It is a current amplifier that has no voltage gain. * It is a negative current feedback circuit. *It has high input impedance low output impedance. *It is used for impedance matching. *It is also known as common collector amplifier. *Circuit diagram: *Circuit details: It consists of transistor Q, biasing resistor Rl R2, emitter resistor RE, input coupling capacitor Cin, biasing supply +VCC, output coupling capacitor CC. Emitter resistance RE acts as the load a. c. output voltage Vo is taken across RE. Here biasing is provided by voltage divider method. lt has no collector resistance no emitter bypass capacitor. *Operation: ac emitter current produces an output voltage across RE. This voltage opposes the input voltage, thus providing negative feedback. The output voltage Vo is equl to input voltage i. e. output voltage follows the input voltage. Hence the name is voltage follower. CHARACTERISTIC OF EMITTER FOLLOWER: *No voltage gain. Practically close to one. *It has high current gain power gain. *Input output ac voltages are in phase.

How to Get Good Grades in Business School

How to Get Good Grades in Business School Every business school works differently when it comes to grades. Some grading systems are based on instructional approaches. For example, lecture-based courses sometimes base grades on class assignments or test scores. Programs that use the case method, like Harvard School of Business, often base a percentage of your grade on classroom participation. In some cases, schools wont even award traditional grades. Yale School of Management, for example, has grading categories like Distinction, Proficient, Pass, and Fail. Other schools, like Wharton, request that professors keep average class GPAs below a certain number, ensuring that only a certain number of students will receive a perfect 4.0. How Important Are Grades in Business School? Before you begin worrying about grades too much, its important to note that GPA isnt really that important if youre an MBA student. Obviously, you want to be able to pass your class and do well, but when it comes down to it, MBA grades just aren’t as important as high school or undergraduate grades. Employers are willing to overlook soft grades for MBA grads who fit the company culture or excel in a particular area, such as leadership. If youre a student in an undergraduate business program, on the other hand, your GPA is important. A low undergraduate GPA can keep you out of a top-ranked graduate school. It can also affect your employment prospects, as employers are much more likely to ask about your class rank and success rate in a particular class. Tips for Getting Good Grades in Business School Determination is an important quality for all MBA students. Without it, you are going to have a hard time wading through the notoriously rigorous curriculum and keeping up with your cohorts. If you can keep your determination level high, your persistence will pay off with good grades or at least an A for effort - professors notice enthusiasm and effort and will find some way to reward it. A few other tips to help you get good grades in business school: Show up for class. You don’t need to attend every single class, but if you attend a small business program, your empty seat will be noticed. Since many business programs are teamwork-based, you will also be letting down your classmates when you do not pull your weight.Participate in class. Remember, participation can account for a large portion of your grade. If you don’t get involved in class discussion or at least look interested in class, you won’t fare well in a case-based curriculum or a course that emphasizes involvement.Learn to read fast. In two years of business school, you could read as many as 50 textbooks and 500 cases. Learning how to take in a lot of dry text in a short amount of time will save you time and allow you to focus on other work.Join or form a study group. Study group members can learn from one another. Making yourself accountable to a group can also keep you motivated and on track.Read case studies. A good case study/analysis combo is th e perfect way to learn how to answer questions in a business school class. If you know what topic you will be studying next week in class, prepare with a few case studies in private this week. Master time management. There is never enough time to get all of your work done in business school. The more you can learn and practice time management, the easier it will be for you to at least get to 90 percent of your work.Network with everyone. Grades are important, but networking is what will help you survive business school and thrive after graduation. Don’t sacrifice your time with other people for hours in the books.