Download GTU BE/B.Tech 2019 Winter 3rd Sem New 2131006 Electronic Devices And Circuits Question Paper

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GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER- III (New) EXAMINATION — WINTER 2019

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Subject Code: 2131006 Date: 30/11/2019
Subject Name: Electronic Devices and Circuits
Time: 02:30 PM TO 05:00 PM Total Marks: 70

Instructions:

1. Attempt all questions.

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2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.

MARKS

Q.1 (a) Explain the second approximation of diode VI characteristics and equivalent circuit. 03
(b) How the depletion layer is formed in unbiased diode? 04

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(c) Draw the circuit of Bridge rectifier and explain the operation of circuit for positive and negative half cycle of input signal. 07

Q.2 (a) What is the difference between rectifier diode and small signal diode? 03
(b) Write a short note on Varactor diode. 04
(c) For a negative biased clipper circuit, input voltage is 5V peak to peak sine wave with frequency of 1KHz. Biased voltage is set at 1.1V. Draw the circuit and input — output waveform for second approximation of germanium diode. 07

OR

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(c) For a positive biased clipper circuit, input voltage is 6V peak to peak sine wave with frequency of 1KHz. Biased voltage is set at 0.9V. Draw the circuit and input — output waveform for second approximation of silicon diode. 07

Q.3 (a) Explain the T Model of a transistor! 03
(b) Use the second approximation to calculate the base current in bellow circuit. What is the voltage-across the base resistor? Find the collector current if ßdc = 200. 04
(c) Explain the voltage divider bias circuit in detail. 07

OR

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Q.3 (a) Draw the circuit of emitter follower and find its AC emitter resistance. 03
(b) For voltage divider bias CE amplifier, find the equation of voltage gain using p Model. 04

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Q.4 (a) Explain Darlington pair connections of two transistors. 03
(b) Explain the difference of class A and class B operation of an amplifier. 04

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(c) Draw the circuit of class B push — pull amplifier and explain its working. List the advantages and disadvantages. 07

OR

Q.4 (a) Draw the symbol of JFET, depletion MOSFET and enhancement MOSFET. 03
(b) Explain the common source amplifier using JFET. 04
(c) What is the frequency response of an amplifier? Explain the decibel power gain and decibel voltage gain with examples. 07

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Q.5 (a) Why JFET is called as voltage controlled device? 03
(b) Explain the four types of negative feedback connections. 04
(c) Explain the structure and biasing arrangements of Enhancement Mode MOSFET for obtaining ID — VDS curve. 07

OR

Q.5 (a) Explain the transconductance curve for JFET. 03

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(b) What is the role of bypass capacitor in voltage divider bias amplifier? 04
(c) Explain the self bias technique for JFET. 07

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