Year: II B.Tech II- Sem EEE
Sub: AEC ( Analog Electronic Circuits )
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UNIT – I
SINGLE STAGE AMPLIFIERS
***1. Analyze general transistor amplifier circuit using h parameter model. Derive the expressions for
AI, AV, Ri, R0, AIs, AVs.( Exp:4M+ Der:6M)
***2. Draw the circuit of an emitter follower, and derive the expressions for AI, Av, Ri, R0 in terms of CE parameters. (.( Dia 4M+ Der:6M))
***3. (a) Sketch the small-signal high-frequency circuit of a CS amplifier and derive the expression for the voltage gain. (Dia:2M+Der:3M)
(b) Sketch the small-signal high-frequency circuit of a CD amplifier and derive the expression for the voltage gain. (Dia:2M+Der:3M)
**4. Write the analysis of a CE amplifier circuit using h parameters. Derive the expressions for AI, AV, Ri, R0,AIs, AVs. ( Anal: 4M+ Der:6M))
**5. (a) The h-parameters of a transistor amplifier shown in figure1. below are hie=1.1 KΩ, hre = 2.5 x 10− 4 , hf e = 50, hoe = 24 μA/V. Calculate AI , AV , AVS,Ro, and Ri [formula:2M,Result: 2M]
Figure:1
(b) Give the analysis of single stage transistor amplifier circuit.(Ckt:2M+Ana:4M)
**6. (a) Draw the low frequency parameter equivalent circuit of a CE amplifier and explain the significance of each parameter. ( Dia 2M+ Exp:4M))
(b) In a single stage CE amplifier RS=1k, R1=50k, R2=2k, RC=1K, RL=1.2k, hfe=50, and hie=1.1k. Find AI , Ri, Ro, and voltage gain. [formula:2M,Result: 2M]
*7. (a) Draw hybrid-π equivalent of a transistor in CE configuration at low frequency.Also
discuss the significance of different parameters of the equivalent circuit. ( Dia 2M+ Exp:4M))
(b) The h-parameter a.c equivalent circuit of a transistor in CE mode is shown in figure 2.Calculate AI , AV = VLVS, Zin and Zout. [4M]
Figure :2
*8. (a) What are h-paraneters? Why they called so? Define them and what are the benefits of h-parameters.(Def:1M+Def:1M+adv:2M)
(b) In a single stage CE amplifier with un bypassed emitter resistance, Rs=1K,R1=50, R2=2K, RC=1K, RE=270, and RL=1.2K. Find AI , AV , Ri and Ro.The h-parameters given are hie=1100, hfe=50. [6M]
UNIT-II
BJT&FET FREQUENCY RESPONSE
***1. (a) Draw the small-signal equivalent circuit for an emitter follower stage at high frequencies and Obtain the voltage gain. [ckt: 2M+der:3M]
(b) Derive the expressions for fβ and fT. [Ckt: 2M+Der: 3M]
***2. (a) Explain why the 3-dB frequency for current gain is not the same as fH for voltage gain. [Reason:2M+Exp:3M]
(b) Derive the expression for the CE short-circuit current gain Ai with resistive load. [Ckt:2M+Der: 3M]
***3. (a) Derive the expression for the CE short-circuit current gain Ai as a function of frequency. [Ckt: 2M+Der: 3M]
(b) Define fβ and fT. Find the current gain with resistive load. [fβ :1M, fT :1M +Der:3M]
**4. Draw the hybrid-pi model, explain and derive the conductance and capacitances. [dia:3M+der:5M+exp:2M]
**5. (a) Draw the hybrid-_ equivalent of a CE transistor valid for high frequency and explain significance of each parameters. [Ckt:4M+Der:6M]
**6. (a) Derive the expression of gain bandwidth product for voltage? [Der:5M]
(b) Short circuit CE current gain of transistor is 25 at a frequency of 2MHz if f_=200kHz. Calculate
i. fT ii. hfe iii. Find |Ai| at frequency of 10 MHz and 100 MHz [ft:2M,hfe:2M,Ai:1M]
*7. (a) Derive the expression of gain bandwidth product for current. [5M]
(b) A HF amplifier uses a transistor which is driven from a source with Rs=0. Calculate value of fH, if RL=0 and RL=1K. Typical values are rb0e = 1K, Ce=100PF and, Cc=3PF and gm=50 mA/V. [5M]
*8. (a) Define fL fH and fT and Derive the relation between fH and fT [Def:2M+Der:3M]
(b) A HF amplifier uses a transistor which is driven from a source with Rs=1K.Calculate value of fH, i_, RL=0 and RL = 2K. Typical values for hybrid-parameters are: rb0e = 1K, bb0 = 100, Ce = 100PF, CC = 3PF and gm =50mA/V. [5M]
UNIT III
FEEDBACK AMPLIFIERS
*1. (a) Classify amplifiers? What is the necessity of feedback? Classify the
Feedback amplifiers?[clas:2M+exp:1M+clas:2M]
(b) Explain the concept of feedback? Give the advantages of feedback?[con:2M+adv:3M]
**2. What are the types of feedback amplifiers? Explain the characteristics
of Negative feedback amplifiers? [type:4M+exp:6M]
**3. Explain the effect of feedback on amplifier characteristics [Ri:2M+Ro:3M+B.W:2M+Av:3M]
** 4. Explain about
i. voltage series [Ckt: 2M+Exp: 3M]
ii. Voltage shunt feedback configurations [Ckt: 2M+Exp: 3M]
***5. Explain about
i. current series [Ckt: 2M+Exp: 3M]
ii. Current shunt feedback configurations [Ckt: 2M+Exp: 3M]
**6. Explain about Positive and negative feedback amplifiers? [positive:2M,negative:3M]
*** 7. (a) Compare the negative feedback and positive feedback. [5M]
(b) How does negative feedback reduce distortion in an amplifier. [Exp:5M]
***8. (a) Describe with necessary derivations, the negative feedback on the band width in an amplifier.[Dia:2M+Der:4M]
(b) An amplifier with stage gain 200 is provided with negative feedback of feedback ratio of 0.05.
Find the new gain.[4M]
UNIT IV
OSCILLATORS
**1. (a) What is an oscillator? What is the need of oscillator?
Write the conditions for oscillations?[def:1M+need:2M+condition:2M]
(b) Write about frequency stability of oscillators?[5M]
***2 (a) Write about RC and LC type Oscillators? [5M]
(b) Write about Amplitude stability of oscillators? [5M]
*3. (a) What are the merits and demerits of phase shift oscillator. [5M]
(b) What is crystal oscillator? Explain about crystal oscillator? [Ckt: 2M+Exp: 3M]
*4. List different type of oscillators? Write about
Frequency and amplitude stability of oscillators? [types:5M+stability:5M]
**5. What is an LC oscillator? Generalize the analysis of LC oscillator? [def:2M+Ana:8M]
***6. Explain about
i. Quartz oscillator[3M]
ii. Hartley Oscillator [4M]
iii. Colpittts oscillator [3M]
***7.Explain and derive an expression frequency of oscillation of RC phase shift oscillator? [ exp:3M+der:7M]
***8.Explain and derive an expression frequency of oscillation of Wien’s bridge oscillator? [ exp:3M+der:7M]
UNIT V
LARGE SIGNAL AMPLIFIERS
***1. (a) In series fed Class - A power amplifier, explain the importance of the position
of operating point on output signal swing. Show that the conversion efficiency is 25%. [Exp:2M+Der:3M]
(b) Discuss the origin of various distortions in transistor amplifier circuits. [Exp:5M]
***2. (a) Classify large signal amplifiers based on their operating point. Distinguish these amplifiers in terms of the conversion efficiency. [Clas:2M+Exp:3M]
(b) Draw the complimentary symmetry class-B power amplifier and explain its operation. [Ckt:2M+Exp:3M]
***3. (a) Draw the circuit of class -A transformer fed power amplifier and derive the
Expression for output power Po. [Ckt:2M+Der:3M]
(b) What is cross over distortion? How can a Class-AB power amplifier avoid cross-over distortion? [Def:2M+Exp:3M]
**4. (a) Write a short note on Transformer coupled amplifier. [Ckt: 2M+Exp: 3M]
(b) Write a short note on Transformer coupled audio amplifier. [Ckt: 2M+Exp: 3M]
**5. (a) Derive the expression for maximum collector Power Dissipation Pc (Max) in the
Case of class B power amplifiers. What is its maximum value?[Der:7M]
(b) Explain the term complementary symmetry. [Exp:3M]
**6. (a) In a class B amplifier VCE min=1V and supply voltage Vcc is equal to 18V.
Find the collector circuit efficiency.[5M]
(b) Write a short note on power output and efficiency of class-A power amplifier. [Po:2M+Eff:3M]
*7. (a) Single ended power amplifier is not used in practical circuit. Instead a push
pull amplifier is used. Why?[5M]
(b) Draw a circuit diagram of a push pull amplifier circuit and explain [Ckt: 2M]
i. how proper biasing is achieved giving circuit.[1.5M]
ii. how AC power free from even harmonics is developed across the load.[1.5M]
*8. (a) Explain about phase inverters? [Ckt: 2M+Exp: 3M]
(b) Explain about transistor power dissipation? [Ckt: 2M+Exp: 3M]
UNIT-VI
LINEAR WAVESHAPING
1.** a) Explain the response of high pass RC circuit with the help of waveforms[High pass circuit-1M]
(i) Pulse input[i/p and o/p waveforms-2M, equations-1M]
(ii) Ramp input[Waveforms for both time constants-1½ M, Equations for both time constants-1 ½ M]
b) Explain the response of high pass circuit with the help of waveforms[High pass circuit-1M]
(i) Exponential input[Waveform-1M, Derivation-2M]
(ii) Square input [Waveform for 3 time constants-1 ½ M,V1,V11,% tilt equation-1 ½ M]
2.**a) Analyze the low pass RC circuit for the following inputs, with the help of wave forms[Low pass ckt-1M]
(i) Pulse[i/p and o/p waveforms-2M, equations-1M]
(ii) Ramp[i/p and o/p waveforms-2M, equations-1M]
b) Analyze the low pass RC for the following inputs with the help of waveforms[Low pass ckt-1M]
(i) Exponential [Waveform-1M, Derivation-2M]
(ii) Square[Waveform for 3 time constants-1 ½ M,V1,V11,% tilt equation-1 ½ M]
3.** a) Draw and explain the circuit of two diode clipper, also draw necessary wave forms.[Circuit-2M,Explanation-2M,waveforms (i/p and o/p transfer characteristics)2M]
b) Explain about diode-differentiator comparator[circuit-1M,explanation-1M,waveforms-2M]
4.** a) Explain about transistor clipper.[Circuit-1M,waveforms-2m, explanation-2M]
b) Explain about effect of diode characteristics on clamping voltage.[Circuit-1M, waveforms-1M,Explanation-1M,Derivation-2M]
5.** a) Explain the need for clamping circuits[Explantion-2M]
b) Choose clamping circuits to give following output [Each Circuit-1M, Explanation-1M]
(i) Positive peaks to be at ‘0’ volts
(ii) Positive peaks to be ‘-V1’volts
(iii)Negative peaks to be ‘0’ volts
(iv) Negative peaks to be ‘-V1’volts
6.*** a) What is meant by clipping in wave shaping? [Explanation-2M,Circuit with wave form-2M]
b) Classify different types of clipper circuits. Give their circuits and explain their operation with the aid of transfer characteristics. [Series clippers with min 3circuits with i/p , o/p, transfer characteristics-3M,
7. ** a) Draw the circuit diagram of Slicer circuit using Zener diode and explain its operation with the help of transfer characteristics. [circuit-2M, Explanation-1M,Waveform-1M]
b) Draw the circuit diagram of Emitter coupled clipper. Draw its transfer characteristics including all intercepts, slopes and voltage levels. Derive the necessary equations.[Circuit-2M, waveform-2M, Explanation, equations-2M]
8. *** a) State and prove Clamping circuit theorem [circuit-1M, Explanation-1M, Derivation-2M]
b) Determine Vo for network shown in figure below for the given waveform. Assume ideal diodes
[Determining two voltage levels-4M, i/p and o/p transfer characteristics waveforms-2M]
UNIT-VII
SWITCHING CHARACTERISTICS OF DEVICES
1.*** Explain the Diode Switch and Diode switching times
[Diode characteristics-2m, circuit-1M,Explanation on diode as switch -2M, Wave form switching-2M]
2.** Explain how the transistor will act as switch[Circuit-2M, O/p Characteristics-2M,explanation-4M, Equations-2M]
3.** For a Common Emitter circuit VCC=10 V, RC=1KΩ, IB=0.2µA.Determine[circuit with all parameters-2M]
(i) the value of hfe (min) for saturation to occur [Ic value-2M,hfe (min) value-2M]
(ii) if Rc is changed to 220Ω, will the transistor be saturated
[Ic value-2M, Condition satisfied/not-2M]
4. ** Discuss piece wise a linear characteristics
[normal diode characteristics-2M, Ideal diode characteristics-2M, Piece wise diode characteristics-2M,Explanation-4M]
5.*** Discuss in detail about transistor Switching times
[circuit-2M, waveform-2M, Explanation-2M,td, ts,tr,tf explanation-4M]
6.** Explain about breakdown voltage considerations of transistor[Breakdown concept explanation-2M,Breakdown in CE, CB configurations explanation with graph-4M, Equations-2M, Explanation-2M]
7.** Explain the phenomenon of Latching in a transistor switch.[graph-4M, Explanation-6M]
8.** Explain the temperature variations of saturation parameters.[ graph-6M, Explanation-4M]
UNIT-VIII
MULTIVIBRATORS
1.** a) Explain about unsymmetrical triggering of Bi-stable multivibrator
[two circuits-2M, explanation for both circuits-3M]
b) Explain the need and usefulness of commutating capacitors in multi vibrator circuit
[circuit-2M, equivalent-1M, Explanation-2M]
2.* Calculate the stable state currents and voltages for fixed bias bi-stable multi vibrator. Assume that the transistor have minimum of hfe value 20. Also draw the necessary equivalent circuits. Also sketch each base and collector voltage. [ KVL equations-2M, VEN1, VEN2-2M,VBN1,VBN2-2M,VCN1, VCN2-2M]
3.*** Find Lower and Upper Threshold voltage for Schmitt trigger circuits with following data. Assume transistors with hfe=30, VCC=12V, RC1=4K, RC2=1K, R1=2K, Rs=1K, R2=6K, Re=3K.
[Circuit-2M, equations-2M, procedure-2M,UTP-2M,LTP-2M]
4.** a) Explain how an schmitt trigger can be used as a squaring circuit
[circuit-2M,operation-2M,input, output waveforms and explanation-3M]
b) What do you understand by hysteresis. What is Hysterisis voltage? Explain how hysteresis can be eliminated in a schmitt trigger.[Hysterisis-1M,Hystersis voltage-1M, Elimination of hysteresis-1M]
5.*** What is a Monostable Multivibrator. Explain with the help of neat circuit diagram, the principle of operation of mono stable multivibrator and derive an expression for pulse width. Draw the waveforms at collector and bases of both transistors.
[Basic concept-2M, circuit-2M, operation-2M, derivation for pulse width-2M, collector and base waveforms for both transistor-2M]
6.** Design a monostable circuit that produces a pulse width of 10msec.(Assume required data).
[Circuit-2M, Data assumption-3M, euqtion-2M, Pulse width-3M]
7.** Design an Astable multivibrator for an output amplitude of 15V and square wave frequency of 500HZ. Assume hfe min=50, Ic(sat)=5mA and VCE(sat)=0V.
[Circuit-2M, Waveform-1M, Equations-2M, R1, R2, C1, C2 values calculation-5M]
8.*** Design a Collector Coupled Astable Multivibrator for the following specifications with silicon transistor. IC(sat)=10mA, hfe(min)=20, Vcc=10V,Pulse width=10µsec, duty cycle=40%.
[Circuit-2M, Waveform-1M, Equations-2M, R1, R2, C1, C2 values calculation-5M]
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