BVRIT HYDERABAD College of Engineering for Women Department of Electronics and Communication Engineering

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Subject Name: BVRIT HYDERABAD Coege of Engineering for Women Department of Eectronics and Communication Engineering Prepared by (Facuty Name): Hand Out Eectronic Circuit Anaysis Mr. G.

1 Subject Name: BVRIT HYDERABAD Coege of Engineering for Women Department of Eectronics and Communication Engineering Prepared by (Facuty Name): Hand Out Eectronic Circuit Anaysis Mr. G. Siva SankarVarma, Asst.Prof, ECE Year and Sem, Department: II Year- II Sem, ECE Unit I: Singe stage and Muti stage ampifiers Ampifier is an eectronic device used to strength the given input signa. Cassification of ampifiers-based on: Type of frequency, feedback, operation, couping etc. Distortion in ampifiers: Votage frequency and deay distortions. Anaysis of CE, CB & CC using hybrid mode to cacuate vaues of A I, R I, A V, Y O. By finding these vaues the manufacturer can estimate and design proper Ampifier circuits. CONFIGURATION VOLTAGE GAIN INPUT RESISTANCE OUTPUT RESISTANCE CB MEDIUM VERY LOW HIGH CURRENT GAIN <1 (LESS THAN 1) CE MEDIUM LOW LOW HIGH CC LOW HIGH VERY LOW HIGH Common Base Configuration:- i) Input and output are in phase. ii) Votage Gain is medium. iii) Current Gain is ess than 1. iv) Ri is very ow. v) Ro is high. vi) Appication: As input stage of mutistage ampifiers. Common Emitter Configuration:- i) Input and output are out of phase. ii) Votage Gain is medium. iii) Current Gain is high. iv) Ri is ow. v) Ro is ow. vi) Appication: For audio signa ampification. Common Coector Configuration:- i) Input and output are in phase. ii) Votage Gain is ow. iii) Current Gain is high. iv) Ri is high. v) Ro is very ow.

2 vi) Appication: For impedance matching. Miers Theorem: The Mier theorem refers to the process of creatingequivaent circuits. It asserts that a foating impedance eement, suppied by two votage sources connected in series, may be spit into two grounded eements with corresponding impedances. Mier theorem heps reduce the compexity in some circuits particuary with feedback by converting them to simper equivaent circuits. Different couping schemes: Used to connect different ampifier configurations- Direct, RC and Transformer couping schemes. RC Couping: i) Couping components are Resistor and capacitor. ii) Bocks D.C iii) Fat at midde frequencies. iv) Appications: Used in radio and teevision receivers. Transformer Couping: i) Couping component is impedance matching transformer. ii) Bocks D.C iii) Frequency response is not uniform. iv) Appications: Used in Pubic Addressing systems. Direct Couping: i) Couping component is impedance matching transformer. ii) Aows D.C iii) Fat at midde frequencies. iv) Appications: Used in DC Ampification. Cascade ampifier- CE-CE or CE-CC etc: Increase bandwidth for high votage ampifiers. Cascode ampifier -CC-CB Increases input impedance and gain. Darington pair-cc-cc: The features are isted beow: i) The current gain of this transistor is high. ii) The input impedance of this circuit is high. iii) These are widey avaiabe in a singe package. Questions 1.Derive the expressions A I, R I, A V, Y O for a transistor in CB configuration using exact hybrid mode? 2. Derive the expressions A I, R I, A V, Y O for a transistor in CE configuration using exact hybrid mode? 3. A Common emitter transistor has h ie =1100Ω, h fe =50, h re =2.5*10-4, h oe =25µA/V. Cacuate A I, Z I, A V, Y O. If R S =1KΩ and R L =1KΩ? 4. A common coector transistor has h ie =1100Ω, h fe =50, h re =2.5*10-4, h oe =25µA/V. Cacuate A I, R I and A V. If R S =1K Ω and R L =10K Ω. 5. Compare different couping schemes used in mutistage ampifiers? 6. Anayze cascading in mutistage ampifiers with an exampe? 7. Anayze cascoding in mutistage ampifiers with an exampe? 8. Discuss Darington pair and derive its necessary expressions? Fi in the banks / choose the Best: is the current gain for a common-base configuration where I E = 4.2 ma and I C = 4.0 ma. 2. The input resistance of CE ampifier is ow. 3. The output resistance of CE ampifier is high.

3 4. Appication of CE configuration is ampification. 5. The input resistance of CC ampifier is high. 6. The output resistance of CC ampifier is ow. 7. Cascading of ampifiers is used to improve the gain. 8. Among a the transistor configurations which is having a ow current gain, common-base. 9. Input and output waveforms of CE configuration is180 out of phase. 10. Among a the transistor configurations which is having a ow votage gain, emitterfoower. 11. An audio ampifier ampifies uptofew KHZ 12. Another name for deay distortion isphase Distortion 13. Couping capacitors mainy used to Bocks DC 14. A current ratio of IC/IE is usuay ess than one and is caed apha 15. Transformer couping in ampifiers mainy used for Impedance matching Unit II: BJT ampifiers and MOS ampifiers Logarithms: In many cases it is convenient to compare two powers on a og scae rather than a inear scae. Decibes: The unit of a og scae is db (decibe). Frequency Response: The graph drawn between Gain and Frequency is said to be the frequency response. By frequency response we can estimate the vaues of Bandwidth. Bandwidth=Higher cutoff frequency-lower cutoff frequency. Couping capacitor is mainy used to bocks DC. Bypass capacitor connected across R E, at mid frequency and high frequency it provides very sma capacitive reactance. When R E is bypassed, the bypass capacitor has no effect on votage gain. By using Hybrid π mode we can anayse high frequency circuits and abe to find foowing parameters: transconductance, base spread resistance, output conductance and feedback conductance. By finding these vaues the manufacturer can estimate and design proper Ampifier circuits. Different parameters from Hybrid π mode: i) transconductanceg m =αi E /V T ii) input conductance g b e =I C /V T h fe iii) spread resistance r bb =hie-(h fe V T /I C ) iv) feedback conductance h re g b e v) output conductance h oe -h fe g b c Differences between BJT and FET: BJT (Bipoar Junctiopn Transistor) FET (Fied Effect Transistor ) 1) Current controed device 1) Votage controed device 2) More noisy 2) Less noisy 3) Switching speed ow 3) Switching speed high 4) Cost is ow 4) Cost is high The foowing are the MOS ampifiers- Common source, Common drain and Common gate ampifiers. Common Source ampifier: Simiar to CE. i) Input Resistance (Ri) = Ri=R G

4 ii) Output Resistance (Ro) = r d R D / rd+r D iii) Votage gain (Av) = -g m r d R D / rd+r D Common Drain ampifier: Simiar to CC. i) Input Resistance (Ri) = Ri=R G ii) Output Resistance (Ro) = r d R D g m iii) Votage gain (Av) = g m Rs Common Gate ampifier: Simiar to CB. i) Input Resistance (Ri) = Ri= 1/g m Rs ii) Output Resistance (Ro) = r d R D iii) Votage gain (Av) = (g m r d +1)R D / r d +R D Questions 1.Anayze Hybrid π mode of transistor CE? 2.Derive the expression for CE current gain? 3.Derive the expression for CE current gain with R L? 4.Evauate votage gain bandwidth product? 5.Identify the reationship between f T and f β? 6.Anayze MOS sma signa mode? Fi in the banks / choose the Best: 1. Formua for transconductanceg m =αi E /V T 2. Formua for input conductance g b e =I C /V T h fe 3. Formua for base spread resistancer bb =hie-(h fe V T /I C ) 4. Formua for feedback conductanceh re g b e 5. Formua for output conductance h oe -h fe g b c 6. Gain Bandwidth Product for votage is f T R L /{[1+2 πf T CcR L ][Rs+r bb ]}. 7. Formua for f β is g m / h fe 2 π (Ce+Cc). 8. Formua for f T is g m / 2 π (Ce+Cc). 9. Reation between f β andf T is f T= h fe f β. 10. f H = f β at oad resistance = Couping capacitor is mainy used to bocks DC 12. Bypass capacitor connected across R E, at mid frequency and high frequency it provides very sma capacitive reactance. 13. WhenR E is bypassed, the bypass capacitor has no effect on votage gain Unit III: Feedback ampifiers and Osciators Feedback in ampifiers is mainy used to improve Bandwidth. If bandwidth is improved the operating range of an ampifier wi be improved. Feedback Cassification: Positive feedback and negative feedback. Negative feedback: The output is out of phase with input signa. Negative feedback ampifiers: Negative feedback ampifiers Input resistance Output resistance Votage Series Increases Decreases Votage Shunt Decreases Decreases

5 Current Series Increases Increases Current Shunt Decreases Increases Positive feedback: The output is inphase with input signa. Exampe for positive feedback is osciators. Osciator is an eectronic device which satisfies Barkhausen criteria. Barkhausen criteria:- 1) Overa phase shift around the oop is 0º/360º. 2) Aβ=1. Type of osciators:- 1) Low frequency osciators: Which generates frequency ess than 20 KHz (f<20khz): i) RC Phase shift osciator: a) The feed backnetworkprovides phaseshift and ampoifier section provides another b) Tota phase shift around the oop is360 0 c) f = 1/(2πRC 6) ii) Wein bridge osciator: a) The feed backnetworkprovides 0 0 phaseshift and ampoifier section provides another 0 0 b) Tota phase shift around the oop is0 0 c) f = 1/(2πRC) 2) High frequency osciators: Which generates frequency greater than 20 KHz (f>20khz): i) Hartey, ii) Copitts and iii) Crysta osciators. Questions 1. Anayze the Negative feedback ampifier and derive A vf? 2. Derive R i and R o for a votage shunt feedback ampifier? 3. Derive R i and R o for a votage series feedback ampifier? 4. Derive R i and R o for a current shunt feedback ampifier? 5. Derive R i and R o for a current series feedback ampifier? 6. Derive frequency of osciations for RC phase shift osciator? 7. 7) An RC phase shift osciator is designed with a frequency of 5kHz and a resistance of 9.7KΩ is used. Cacuate the vaue of capacitance? 8. Derive frequency of osciations for Wein Bridge osciator? 9. A Wein Bridge osciator has a frequency of 500Hz if vaue of capacitance is 100pF. Cacuate vaue of resistance? 10. Derive frequency of osciations for Hartey osciator? Fi in the banks / choose the Best: 1. Parae resonant frequency is approximatey 1 khz higher than series resonant frequency. 2. The formua for input resistance of votage series feedback ampifier is R if = R i (1+βA v ). 3. The formua for input resistance of current series feedback ampifier is R if = R i (1+βG M ). 4. The formua for output resistance of current shunt feedback ampifier is R of = R o (1+βA i ). 5. The formua for output resistance of votage shunt feedback ampifier is R of = R o /(1+βR m ). 6. For a wein bridge osciator frequency required for osciations is f= 1/2πRC 7. For a copitts osciator frequency required for osciations is f= 1/2π (LC eq ) (or) 1/{2π(LC eq ) 1/2 }.

6 8. For an RC osciator frequency required for osciations is f= 1/{2πRC 6}. 9. The feedback signa in a copitts osciator is derived from a capacitive votage divider in the LC circuit. 10. Sinusoida osciators operate with positive feedback. 11. Barkhausen criteria states that overa phase shift around the oop is0º/360º 12. The type of ampifier used in RC phase shift osciator is Inverting ampifier 13. The type of ampifier used in Wein bridge osciator is Non inverting ampifier 14. The input resistance of votage shunt feedback ampifier is decreases 15. The input resistance of current shunt feedback ampifier is decreases Unit IV: Large signa ampifiers Large signa ampifier:- Which ampifies both votage and frequency eves. Appications:- Mainy used in PA (Pubic addressing systems). Cassification:- 1) Cass A and 2) Cass B etc. 1) Cass A:-Cass A ampifier is a type of power ampifier where the active device (transistor) conducts ony for fu cyce of the input signa. That means the conduction ange is 360 for a Cass A ampifier. Types of Cass A:- i) Direct Couped & ii) Transformer Couped Cass A power ampifiers. i) Direct Couped Cass A Power ampifier: a) Easy to design. b) Cost is ow. c) Efficiency is: Idea case 25% and Practica case 15% ii) Transformer Couped Cass A Power ampifier: a) Compicate to design. b) Cost is high. c) Efficiency is: Idea case 50% and Practica case 30 to 35% 2) Cass B:-Cass B ampifier is a type of power ampifier where the active device (transistor) conducts ony for one haf cyce of the input signa. That means the conduction ange is 180 for a Cass B ampifier. Efficiency of Cass B:Idea case 78.5% and Practica case 65 to 70% Compared with Cass A, Cass B is more efficient. Types of Cass B:- i) Push-Pu & ii) Compementary Symmetry Push-Pu Cass B power ampifiers. Comparision between Cass A and Cass B: Parameter Cass A Cass B Operating Cyce Efficiency Low Better Distortion Absent Present Power Dissipation Very high Low Heat sink: Used to dissipate the deveoped heat in the transistor. It carries the heat to surroundings.

7 Questions 1.Expain series fed cass A power ampifier with necessary equations, advantages and disadvantages? 2.Cacuate the input power, output power and efficiency of cass A power ampifier which is shown beow. The input votage causes a base current of 5mA and assume V BE =0.7V? VCC 18V RB 1.2kΩ RL 16Ω C β=40 Vin 3. 4.Expain Transformer couped cass A power ampifier with necessary equations, advantages and disadvantages? 5.Expain push pu cass B power ampifier with necessary equations, advantages and disadvantages? 6.Expain compementary symmetry push pu cass B power ampifier with necessary equations and advantages? 7.A singe transistor operates as an idea cass B ampifier. If DC current drawn from the suppy is 25mA. Cacuate AC power deivered to the oad for R L of 2KΩ 8.Expain about Distortion in power ampifiers briefy? 9.For harmonic distortions of D 2 =0.1, D 3 =0.02 and D 4 =0.01 with fundamenta component of I1=4A and RL=8Ω. Cacuate: a. Tota harmonic distortion. b.fundamenta power component. c. Tota power. Fi in the banks / choose the Best: 1. In cass A power ampifiers, the output signa varies for a fu 360º of the cyce. 2. Cass D ampifiers have the highest overa efficiency. 3. Cass A power ampifiers has the owest overa efficiency. 4. Cass D operation can achieve power efficiency of over 90%. 5. The fundamenta component is typicay arger than any harmonic component. 6. The junction has the hottest temperature in a power transistor. 7. Both npn and pnp or nmos and pmos transistors can be used to buid a cass B ampifier. 8. A heat sink provides a ow therma resistance between case and air. 9. In tuned ampifiers harmonic distortion is ess. 10. Generay tuned ampifiers are used in RF ampifiers and communication receivers. 11. This is an exampe of the output swing for a Cass B ampifier

8 12. The main features of a arge-signa ampifier isthe circuit's power efficiency, maximum power imitations and impedance matching to the output device. 13. What is the ratio of the secondary votage to the primary votage with the turn ratio in the windings N2/N1 14.Cass AB ampifiers are normay operated in a push-pu configuration in order to produce an output that is a repica of the input. 15. Which type of power ampifier is biased for operation at ess than 180º of the cyce is Cass C Unit V: Tuned ampifiers Tuned Ampifier: An ampifier with tuned circuit is said to be tuned ampifier. The tuned circuit is capabe of ampifying a signa over a narrow band of frequencies. Resonant frequency Fr = 1/2π (LC) Q factor: It is a measure of efficiency with which inductor can store the energy. Q factor is inversey proportiona to dissipation factor (D). 3dB bandwidth is the ratio of resonasnt frequency to effective Q factor. Cassification of tuned ampifiers: Singe tuned, ii) Doube tuned & iii) Stagger tuned ampifiers Singe tuned ampifier: Effect of cascading in singe tuned ampifiers can be expained by the foowing formua. (B.W)n = BW 1 (2 (1/n) -1); n no of stages. Doube tuned ampifier: Two singe tuned ampifiers are cascaded. Effect of cascading in doube tuned ampifiers can be expained by the foowing formua. (B.W)n = BW 1 *(2 (1/n) -1) 1/4 ; n no of stages. Differences between Synchronous and Stagger tuned ampifiers. Synchronous tuned ampifier 1) The overa bandwidth is ower than that of a singe tuned circuit aone. 2) Magnitude is more 2) Magnitude is ess 3) Pass band is narrow 3) Pass band is wider Stagger tuned ampifier 1) The overa bandwidth is greater than that of a singe tuned circuit aone. Stabiity: Stabiity of tuned ampiers is improved by the foowing techniques: i) Hazetine Neutraization. ii) Missmatch technique.

9 iii) Neutrodyne Neutraization. Questions 1.Design a singe tuned capacitive couped ampifier? 2.Discuss effect of cascading singe tuned ampifiers on band width? 3.Compare synchronous tuning and stagger tuning? 4.Expain Hazetine neutraization technique? 5.Band width for a singe tuned ampifier is 20KHz. Cacuate bandwidth of 3 stages is cascaded and aso cacuate bandwidth of 4 stages? 6.Band width for a doube tuned ampifier is 20KHz. Cacuate bandwidth of 4 stages is cascaded? Fi in the banks / choose the Best: 1. A tuned ampifier is generay operated in Cass Coperation 2. A tuned ampifier is used in Radio frequency appications 3. Frequencies above 200 khz are caed radio frequencies 4. At series or parae resonance, the circuit power factor is 1 5. The votage gain of a tuned ampifier is Maximum at resonant frequency 6. At parae resonance, the ine current is Minimum. 7. At series resonance, the circuit offers Minimum impedance 8. A resonant circuit contains L and C eements 9. At series or parae resonance, the circuit behaves as a Resistive oad 10. At series resonance, votage across L is Equa to but opposite in phase to votage across 11. When either L or C is increased, the resonant frequency of LC circuit decreases 12. At parae resonance, the net reactive component circuit current is Zero 13. In parae resonance, the circuit impedance is L/CR 14. In a parae LC circuit, if the input signa frequency is increased above resonant frequency then X L increases and X C decreases 15. If L/C ratio of a parae LC circuit is increased, the Q of the circuitisincreased

BVRIT HYDERABAD College of Engineering for Women Department of Electronics and Communication Engineering

BVRIT HYDERABAD College of Engineering for Women Department of Electronics and Communication Engineering BVRIT HYDERABAD Coege of Engineering for Women Department of Eectronics and Communication Engineering Hand Out Subject Name: Anaog Eectronics Prepared by (Facuty Name): Mr.M.Venkatesh, Asst.Prof, ECE Year