VTU 10CS32 Question Bank

7/23/2019 VTU 10CS32 Question Bank

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Electronic Circuits 10CS32

Dept. of CSE, SJBIT 1

VTU QUESTION BANK

UNIT-1: TRANSISTORS, UJTs, AND THYRISTORS

1. With neat figure, explain the construction and operational principle of an Unijunction

Transistor (UJT). (10 marks) (July 2013)

2. Explain the effects of collector resistor, base current and supply voltage on the

operating point of a fixed bias circuit. Which is the ideal position for an operating

point on the BJT fixed bias transistor circuit? Explain the above with neat diagrams.(10 marks) (June 2012)

3. What is the operating point for the following voltage divider bias circuit?

(10 marks) (June 2012)

4. Sketch and explain with the circuit, the combination clippers which limit the

output between 5V.Assume diode voltage is 0.7V. (10 marks) (June 2014)

5.What is Clamping? With neat diagram and waveform, explain the working of

negative clamper and also write the condition for stiff clamper.

(7 marks) (June 2014)

6. Explain Varactor diode with its characteristic curves. (3 marks) (June 2014)

7. Find the values of resistors Rb, Rc,Re and the transistor gain , for the circuit.

Ib=40A, Ic=4mA, Ve=2V, Vce=12V, Vcc=15V. Assume that the transistor used in the

circuit is a silicon transistor. (10 marks) (July 2013)

8. Explain transistor in its fixed bias mode with relevant expression.

(10 marks) (Dec 2012)

9. With a neat sketch, explain transistor as a switch. (5 marks) (Dec 2012)


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10. For the circuit shown calculate IB, IC, VCE, VC, VE, VB. Assume = 100.

(5 marks) (Dec 2012)

11. Explain the criteria for selecting a suitable operating point and factors affecting the

stability. (10 marks) (Dec 2013)

12. Find the values of resistance RB, RC, RE and transistor gain , for the circuit shown in

Fig.Q1(b). Given that IB = 40 A, IC = 4mA, VE = 2V, VCE = 12V and supply voltage VCC

= 15V. Assume that the transistor used in the circuit is a silicon transistor.

(6 marks) (Dec 2013)

13. Explain transistor as a switch. (4 marks) (Dec 2013)


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UNIT-2: FIELD EFFECT TRANSISTORS

1. Explain the working of a N-channel E-Mosfet with neat diagram. Explain with a

Diagram output characteristics of the same. (10 Marks)(June 2012)

2. Find the values of voltages VD and VC for the circuit shown, Fig.Q2(b). Assume b =

100, VBE = 0.7 V, saturation drain current of JFET is 10 mA and pinch off voltage is-

5V. (4 Marks)(June 2012)

3. With circuit diagram, explain base bias amplifier and give the importance of capacitor.

(6 Marks)(June 2012)

4. Explain the small signal operation of amplifiers. (10 Marks)(June 2011)

5. For the circuit given below fig.Q2(c), (i) Calculate the input impedance of the base

with = 100; (ii) Draw the DC equivalent circuit; (ii) Draw the AC equivalent circuit

using T and model.


6. Explain the VI characteristics of n-channel JFET and define various conditions .

(10 Marks)(Dec 2012)

7. Mention merits and demerits of IGBT. (10 Marks)(Dec 2012)

8. What are the differences between JFET & MOSFET. (10 Marks)(June-July 2013)

9. With the help of neat figures, explain the construction and characteristics of N-channel

depletion MOSFET. (10 Marks)(June-July 2013)

10. How Biasing configuration using De-MOSFET work. Justify. Given that saturation

drain current is 8mA, and the pinch off voltage is -2V. Determine the value of gate source

voltage, drain current and the drain source voltage. (10 Marks)(June-July 2013)

11. What are the difference between BJTs and FETs? (10 Marks)(Dec 2013)

12. Explain the working of a CMOS inverter. (10 Marks)(Dec 2013)

13. Explain the construction .working and principle of operation of an n-channel JFET.



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UNIT-3: OPTOELECTRONIC DEVICES

1. Explain photodiode, photosensor, photo conductor and phototransistors with necessary

diagrams. (10 Marks)(June 2012)

2. Find the value of RL for the circuit shown, Fig.Q3(b) such that the circuit gives a logic

high when the light incident on it is above 200 lux and the photo conductor has a resistance of

14kW at a light level of 100 lux, a = 0.5, power supply voltage is VCC = 10V and reference

voltage of zener diode is 3.5V. (10 Marks)(June 2012)

3. What is multistage amplifier? With the neat circuit diagram explain two stage

CE amplifier and derive equation for voltage gain. (10 Marks)(June 2014)

4. For the swamped amplifier shown fig.Q3(b) below, calculate; (i) Input impedance of the

base; (ii) The input impedance of the stage; (iii) AC input voltage to the base; (iv) Voltage

gain; (v) AC voltage across the load. (10 Marks)(June 2014)

5. Explain the construction and working of phototransistor and mention its applications


6. What are optocouplers? Explain the working and characteristics of optocoupler.

(5 Marks)(Dec 2012)

7. Define the following terms: (i) Responsivity (ii) Detectivity (iii) Quantum efficiency (iv)

Noise equivalent power (v) Response time. (5 Marks)(Dec 2012)

8. What is Phototransistor? Draw a schematic symbol of a phototransistor. Explain the V- I

characteristics also. (10 Marks)(June-July 2013)

9. Explain different modes of operation of an LCD display. (10 Marks)(June-July 2013)

10. Discuss the classification of optoelectronic devices, in detail.

(7 Marks)(Dec 2013)

11. Explain with neat diagrams, the principle of operation, characteristics, advantages,

disadvantages and applications of a photodiode. (8 Marks)(Dec 2013)

12. Briefly discuss with necessary diagrams, the basic operation and construction of LED.

(6 Marks)(Dec 2013)


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UNIT-4: SMALL SIGNAL ANALYSIS OF AMPLIFIERS

1. Graphically how h-parameters of a BJT are determined? Explain with neat diagram. Also

derive expression for input impedance and voltage gain for a BJT amplifier.


2. Give the hybrid equivalent model for the circuit shown, in Fig.Q4(b). Find input

impedance,voltage gain, current gain and output impedance. The h-parameters are hie = 1.5k,

hje = 100, hre = 1104, hoe = 25m A/V. (10 Marks)(June 2012)

3. Explain the classification of amplifiers based on their operation.


4. Draw the DC load line and AC load line for a VDB amplifier.


5. With the circuit diagram explain push pull power amplifier and list the advantages and

disadvantages of push pull amplifier. (6 Marks)(June 2014)

6. Derive expression for Ai, Zi, Av, Yo, Ap for a transistor amplifier using h-parameter

model. (10 Marks) (Dec 2012)

7. Explain the need for cascading amplifier and with the block diagram, explain two stage

cascaded amplifier. (10 Marks)(Dec 2012)

8. Draw the generalized h-parameter model of a transistor based amplifier and derive the

expression for Current gain, Input Impedance, Voltage Gain & Output admittance.

(8 Marks)(June-July 2013)

9. With a neat diagram, Explain the operation of Darlington Amplifier.


10. What are cascade amplifiers? What are the advantages offered by the amplifier.

(6 Marks)(June-July 2013).


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11. Explain the need for cascading amplifier and with the block diagram, explain two stage

cascaded amplifier. (10 Marks)(Dec 2013)

12. Obtain the expression for current gain, input impedance voltage gain, output impedance

Power gain of a transistor amplifier using complete hparameter model.



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UNIT 5: LARGE SIGNAL AMPLIFIERS, FEEDBACK AMPLIFIER

1. Large signal amplifier characteristics. Discuss harmonic distortion. Derive A2, A3, A4,

the amplitude of D,C, first, second, third, forth amplitude of harmonic components.


2. Derive expressions for gain, input resistance and output resistance of voltage shunt

Feedback amplifier with the help of neat diagram. For the opamp based inverting amplifier

circuit shown in Fig.Q5(b) find input impedance given that transimpedance, input

impedance and output impedance of opamp are 100 MW, 10 MW, and 100 W respectively.


3. Explain Voltage series feedback. (8 Marks)(June 2014)

4. What are the Advantages and Disadvantages of negative feedbacks.


5. Describe Shunt Feedback. (6 Marks)(June 2014)

6. Explain different FB amplifiers. (8 Marks)(Dec 2012)

7. With the block diagram, explain the negative feedback in small signal amplifier.

(6 Marks)(Dec 2012)

8. An amplifier having a voltage gain of 60dB uses 1/20th of its output in negative feedback.

Calculate the gain with feedback, the percentage change in gain without and with feedback

consequent on 50% change in gm. (6 Marks)(Dec 2012)

9. What are the advantages of negative feedback.? (5 Marks)(July 2013)

10. Derive the relevant expression to prove that input resistance increases and output

resistance decreases in case of voltage series feedback. (8 Marks)(July 2013)

11. Consider Opamp based inverting amplifier circuit. Identify the negative feedback.

Determine the trans impedance gain, the input impedance and output impedance of the

amplifier. The parameters are 100M,10Mand 100respectively.

(7 Marks)(July 2013)


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12. What is ohmic region of EMOSFET? With the circuit diagram determine whether the

MOSFET is based in the ohmic region. (7 Marks)(Dec 2013)

13. The EMOSFET in the circuit fig.Q5(b) has following parameters V= 4.5V = 75mA and

RDS(ON)=10W. Calculate the output voltage. Show the equivalent circuit.

(8 Marks)(Dec 2013)

14. Discus in detail CMOS Operation and power consumption. (5 Marks)(Dec 2013)


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UNIT-6: SINUSOIDAL OSCILLATORS, WAVE-SHAPING CIRCUITS

1. Mention the conditions necessary for oscillations in a feedback amplifier circuit.

Determine the frequency at which the following circuit, shown in Figure would oscillate if

the loop gain criterion was met. Also determine the maximum value of R1 for sustained

oscillation. (10 Marks)(June 2012)

2. With neat diagram and waveforms explain the working of a bistable multivibrator (BJT

based). (10 Marks)(June 2012)

3. Explain Monostable Multivibrator. (7 Marks)(June 2014)

4. Describe Low Pass Filter. (7 Marks)(June 2014)

5. Explain Barkhausen Criteria. (6 Marks)(June 2014)

6. Explain the construction and working of RC phase shift oscillator.

(8 Marks)(Dec 2012)

7. Find the frequency of the oscillations of a Colpitts oscillator having C1 = 150pF, C2 = 1.5

nF and L = 50H. (7 Marks)(Dec 2012)

8. With a circuit diagram, explain the working of RC low pass and RC high pass circuits.

(5 Marks)(Dec 2012)

9. Explain the Barkhausen Criterion as referred to oscillators.


10. With a neat figure explain the operation of voltage controlled oscillator.


11. With neat figure and relevant waveforms explain the operation of Astable multivibrator

using 555 IC timer. (7 Marks)(June-July 2013)

12. Draw the frequency response diagram of an AC amplifier and identify cut off frequency,

mid band gain. (8 Marks)(Dec 2013)


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13. Define DECIBEL power gain, DECIBEL voltage gain. For the cascaded amplifier

shown below, calculate the decibel voltage gain of each stage and the overall decibel

gain. (6 Marks)(Dec 2013)

14. Explain the various types of negative feedback amplifiers.



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UNIT-7: LINEAR POWER SUPPLIES, SWITCHED MODE POWER SUPPLIES

1. Explain regulated power supply parameters: Load regulation, line regulation, output

impedance. Ripple rejection factor. Determine the output ripple of a regulated power supply

which provides a ripple rejection of-80dB and a ripple voltage in the unregulated input were.


2. Explain buck regulator boost regulator and inverting regulator with neat diagram.


3. Describe the operation of Buck Regulator. (10 Marks)(June 2014)

4.


5. Define the following. i) Load Regulation ii) Output Impedance iii) Ripple Rejection

Factor (5 Marks)(June 2014)

6. Explain the construction and working of SMPS and mention different types of switching

Regulators. (10 Marks)(Dec 2012)

7. Define the terms load regulation, line regulation and output resistance for a voltage

regulator. (10 Marks)(Dec 2012)

8. Name the constituent parts of a linear regulated power supply. Describe the following

terms. (5 Marks)(June-July 2013)


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9. Define Load regulation, Line Regulation, Ripple rejection factor, with respect to regulated

power supplies. (5 Marks)(June-July 2013)

10. Explain the working of a Buck regulator. (5 Marks)(June-July 2013)

11. Consider three terminal regulator circuit. Determine Load current, Current through

LM7812 Current through external transistor and Power dissipated in LM7812 with

Vbe=0.7V. (5 Marks)(June-July 2013)

12. Explain the steps involved in custom design of mains transformer.

(6 marks )(Dec 2013)

13. What are SMPS? Compare linear power supplies with SMPS.

(7 Marks )(Dec 2013)

14. Explain the working of three terminal voltage regulator.

(7 marks )(Dec 2013)


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UNIT-8: OPERATIONAL AMPLIFIERS

1. Explain with neat diagram: i) Peak detector circuit ii) Absolute value circuit and their

working. (10 Marks)(June 2012)

2. Explain with neat diagram: i) Current to voltage converter ii) Voltage to current

converter and their working. (10 Marks)(June 2012)

3. Explain Input Impedance. (8 Marks)(June 2014)

4. With circuit diagram explain zero crossing detector. (6 Marks)(June 2014)

5.


6. With relevant formulas, neat diagram and wave form explain op-amp Schmitt trigger.


7. Define the following terms of Op-amp: CMRR, PSRR, Slew Rate, Bandwidth and Open

Loop Gain. (5 Marks)(June-July 2013)

8. With a neat diagram explain the operation of a peak detector circuit using op-amp.


9. Explain the Relaxation Oscillator circuit working with a neat circuit and its waveforms

using Op- amp. (8 Marks)(June-July 2013)

10. Discuss the requirements of a good instrumentation amplifier.

(4 Marks)(Dec 2013)

11. Explain the of an OPAMP window comparator with circuit diagram.

(8 marks)(Dec 2013)

12. Explain the lead and lag type of phase shifter. (8 marks)(Dec 2013)

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VTU 10CS32 Question Bank