Calicut University 2007 B.Sc Computer Science second year , - Question Paper
second year B.Sc degree examination, may 2007
SECOND YEAR B.Sc. DECREE EXAMINATION, MAY 2007
Part iii Electronics Paper I- -El,ECTEONiC DEVICES AND CIRCUITS Time : Three Hours Maximum : SO Mark.
Fart A
Answer any five of the following questions.
1. Distinguish between Direct and Indirect semiconductors.
2. Distinguish between Step and Graded junction.
3. Write short note on tunnel diode.
4. Write down the relation between n, gm and rd of a FET.
6. Draw a common base configuration, also draw I/P and O/P characteristics.
6. What is the significance of a varactor diode.
7. Explain the baising of FET. .
__________- ,v. (5 x 3 = 15 marks)
Answer any three of the following questions.
1. Describe the energy band diagram of insulators, conductors and semiconductors.
2. Show that the probability of a state AE above EF is-filled equals the probability that a state AE below EF is empty.
3. Explain the operation of a impact diode. ; j r*<.*, .
4. Compare CE, CB and CC configurations in terms of voltage gain, current gain input resistance and output resistance.
5. Write short note on transferred electron devices.
(3 x 5 = 15 marks)
Answer any one of the following.
1. A Ge sample is doped with 1017 Boron atoms per cm.3 Determine the carrier concentrations and fermi level position at room temperature ni for Ge = 2.5 x 1013 cm.-3 at room temperature.
2. Explain all biasing circuits of BJT, compare the performance.
Part B
Answer any five of the following questions.
1. Derive the expression for ripple factor o:'half wave rectifies
2. Give the concept of gain band width pro&uct.
3. Write short note on emitter follower configuration.
4. Draw the circuit of a RC integrator. Draw the O/p waveform for a Bquare wave I/P.
5. Draw the circuit of a class C amplifier alnd briefly explain its application.
6. Compare BJT and FET,
7. Write short note on crystal oscillator.
(5 x 3 = 15 marks)
Answer any three of the following questions.
1 Explain various full wave rectifier circuits?'
2. Draw the circuit of a Colpitts oscillator and give the expression for frequency of oscillation.
3. Draw the circuit of a RC coupled ampliftr and explain its working.1
4. List the advantages of negative feedback.
5. In a transistorised Hartley oscillator the two inductances are 2 mH and 20nH. While the frequency is to be changed from 950 kHz to 2050 kHz. Calculate the range over which the capacitor is to be varied.
(3 x 5 = 15 marks)
Answer any one of the following.
1. Explain the working of RC phase shift oscillator and derive the expression for frequency of oscillation.
2. Explain the operation of class A amplifier and derive the expression for efficiency.
(1 x 10 = 10 marks)
C 31149
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| Earning: Approval pending. |
