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EEC 3rd Sem
Analog and Digital Electronics 2010-11
EEC309 B. Tech.
(SEM III) ODD SEMESTER THEORY EXAMINATION 2010-11
ANALOG AND DIGITAL ELECTRONICS
Time : 3 Hours Total Marks : 100
Note : Attempt all questions. All questions carry equal marks
1. Attempt any four parts of the following :
(a) Explain the operation of a LED with the help of necessary diagrams. List the materials used for constructing LED. Give the advantages and disadvantages of LED.
(b) Explain the forward and reverse characteristics of a Tunnel diode and explain the tunneling operation.
(c) Explain the characteristics of a varactor diode and mention how it can be used in a resonant circuit. Also list some of the applications of the varactor diode.
(d) Explain the construction, operation and l-V characteristics ofaSchottky diode. Also give its equivalent circuit diagram and circuit symbol.
(e) With the help of a neatly labeled circuit diagram explain the switching operation of a transistor. Also give the switching waveforms.
2. Define and explain the following terms in case of a photo detector:
(g) Quantum Efficiency
(i) Dark Current.
Attempt any two parts of the following:
(a) Why h-parameters could not be used for high frequency analysis of the transistors ? Give the hybrid-rc equivalent circuit of a Bipolar Junction Transistor, explaining the significance of the terms appearing in the circuit. Define the following — fa, f? and fT and derive the relationship between fa and fp.
(b) Give the high frequency small-signal circuit of a MOSFET with load resistance showing the effect of Miller capacitance. Also derive an expression for the Miller Capacitance and cut-off frequency (fT).
(c) What are the general properties of Negative feedback ? And explain how negative feedbacks can be used for input resistance, output resistance, and bandwidth stability.
1. Attempt any two parts of the following:
(a) Explain the Barkhausen criteria for oscillators. And also
derive the necessary conditions required for oscillations. What are the factors on the basis of which oscillators are classified?
3. Design an RC phase shift oscillators using BJT for a frequency of I kHz. The stability factor S < 8. Given that Vcc = 10 V. The transistor has h-parameters as follows — h = 1 kQ. h. = 50, h =h =0.te ’ fc 7 re oe
4. Explain the operation of a Wien-Bridge oscillator and derive the necessary condition for oscillation. Give the equivalent circuit of a crystal and give the advantages of a crystal oscillator.
(j) Attempt any four parts of the following:
- Define combinational circuit. Realize the following expression f (A, B, C) = Zm (0, 2, 4, 6) using a 4 : 1 multiplexer.
- Explain the difference between Latch and Flip-Flop. Explain how a D Flip-Flop is obtained from a JK. Flip-Flop.
- Design a 3-bit Bi-Directional Shift resistor using JK Flip-Flop.
- What is a universal shift register ? Explain its operation with the help of a logic diagram showing all the necessary signals.
- Differentiate between synchronous and asynchronous counter. Give the logic diagram of a BCD counter.
(0 Explain the operation of a Johnson counter using D Flip-Flop.
(k) Attempt any four parts of the following :
(a) Give the circuit diagram of a Non-inverting Schmitt Trigger
and derive the expression for Hystersis voltage.
5. Explain the operation of a Astable Multivibrator circuit using an Op-Amp. Also derive the expression for cut off frequency.
6. Give the functional block diagram of timer IC 555 and explain how it can be used to obtain a Monostable Multivibrator.
7. Distinguish between A/D and D/A converters. Explain the operation of any one of them.
8. Give the circuit diagram of a sample and hold circuit and explain its operation.
9. Explain the procedure for obtaining a 32 x 4 memory using 16 x 4 memory chips. Also show the necessary circuit diagram.