Subject Code: 141101
GUJARAT TECHNOLOGICAL UNIVERSITY
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BE - SEMESTER-IV (OLD) EXAMINATION - WINTER 2018
Subject Name: Advance Electronics
Time: 02:30 PM TO 05:00 PM
Instructions:
- Attempt all questions.
- Make suitable assumptions wherever necessary.
- Figures to the right indicate full marks.
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Q.1
(a) Draw hybrid p equivalent circuit for common emitter transistor. Also derive the expression for input conductance (gb’e ). [07]
(b) What is feedback? List the advantages of negative feedback. Derive relation between gain with and without feedback in a transistor amplifier. [07]
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Q.2
(a) Explain briefly the following terms: [07]
(1) Virtual Ground concept of OP-AMP (2) “Barkhausen criteria” for oscillator circuit.
(b) Draw hybrid p circuit for a single stage CE transistor amplifier having load resistance RL and obtain expression for short-circuit current gain and bandwidth. [07]
OR
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Q.3
(a) Define the following terms: [07]
(1) Common Mode Gain (2) Differential Gain (3) PSRR (4) Noise margin (5) fan-out (6) Common Mode Rejection Ratio (7) Figure of merit for logic families
(b) Three cascaded stages amplifier have an upper 3 dB frequency of 16 KHz and a lower 3 dB frequency of 25 Hz. What are the values of fL and fH of each stage? Assume that all the stages are identical. Also calculate the bandwidth of each stage. [07]
Q.4
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(a) Explain in detail two stages-RC coupled amplifier with its frequency response. [07]
OR
(b) For the voltage amplifier Av = 140, f1=200 Hz, fH = 200 KHz, Ri = 2KO, Ro =4.7KO. When negative feedback is employed in it with ß = 0.4, determine the Af, Rif, Rof, FLf, FHf. [07]
Q.4
(a) Explain important characteristics of ideal Op-Amp. [07]
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(b) Draw the symbol and AC equivalent circuit of a Crystal oscillator and explain the principle of operation of Crystal Oscillator. [07]
Q.5
(a) What is the significance of CMRR? List and explain the methods to improve the CMRR. [07]
OR
(b) Draw the equivalent circuit of a practical OP-AMP and explain the significance of each component shown in it. [07]
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Q.5
(a) Draw op-amp based Wien bridge oscillator. Obtain frequency of oscillation and discuss amplitude stabilization for the same. [07]
Date: 05/12/2018
Total Marks: 70
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(a) Explain the working principle of Digital to Analog convertor and Explain R-2R Digital to Analog convertor. Also give the advantages and disadvantages of R-2R Digital to Analog convertor. [07]
(b) Explain in detail two input TTL-NAND Gate (Totempole Output) [07]
OR
Q.5
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(a) Tabulate the compare of TTL, CMOS, and ECL logic families based on speed, fan-in, fan-out, noise immunity, power dissipation, and application. [07]
(b) Explain working of successive approximation ADC with block diagram. [07]
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