Calicut University 2007 M.Sc Physics PHY 104 - ELECTRONICS - Question Paper
FIRST SEMESTER M.Sc. DEGREE EXAMINATION, JANUARY 2007
Physics
PHY 104 - ELECTRONICS
(2005 admissionS)
27880 Name:
RegJVo.
FIRST SEMESTER M.Sc. DEGREE EXAMINATION JANUARY, 2007
Physics PHY 104 ELECTRONICS (2005 admissions)
Time: 3 hours maximum: 80 Marks
SECTION- A
(Answer any FIVE questions. Each question carries four marks)
e 1. Explain how an FET can be used as a VVR. Give any one application of a VVR.
2. Explain why it is possible to obtain amplification by using a device which exhibits negative resistance.
3. What is the significance of the terms quantum efficiency and response speed in the performance of a photodiode.
-Y
l4. What does the term roll-off mean? What problem can occur with an amplifier with a steep gain roll-off?
5. Compare the advantages and disadvantages of Dominant pole and Pote-Zero compensation techniques used in Op-Amp circuits.
y 6. What are the limitations of an ordinary OP-Amp differentiator? Draw the circuit of a practical differentiator that will eliminate these limitations.
7. What is meant by the terms modulus and natural count of a counter? How many flip flops are required to have a natural count of 32?
8. What are the important features of an optical memory?
(5x4=20 marks)
SECTION-B (Answer BOTH questions. Each question carries 20 marks)
9. A) 1. What are the conditions required by the transferred electron mechanism to give rise to a negative differential resistance region? (6 marks)
2. Obtain expression for the dielectric relaxation time for a semiconductor in terms of the negative differential mobility. (10 marks)
(3) What'are5 8ie advantages of TEDs over IMP ATT diodes? (4 marks)
' . A 0
OR
B) (1) With die"help of energy band diagrams, describe how population inversion ' can be achieved in a semiconductor LASER. Hence show that direct band gap materials are preferred for semiconductor LASER * (14 marks)
(2) What is optical confinement? Give expression for confinement factor.
(6 marks)
10. A) (1) Define pass band and stop band. (4 marks)
(2) Explain why we use higher order filters. (4 marks)
(3) Discuss with theory the operation of a first order high pass filter using
Op - Amp 741 and give its Butter Worth response. (12 marks)
t\
OR
p<"X B With a neat block diagram describe the CPU architecture of INTEL 8085 processor.
v (2 x 20 = 40 marks)
Section C
Answer any two questions
Each questions carries 10 marks.
11. In the given circuit, Rg = 100Q,R<j= 1.2KD, Vdd~ 16V, Rl= 1MQ and Rg = 1MQ. The FET data sheet gives, loss = 8 mA and Vp = - 4 V. Determine the voltage gain, input resistance and output resistance.
rl
r
i
12. For the inverting amplifier using Op-Amp 741, determine the maximum possible output offset voltage due to (1). The input offset voltage Vjo (2). The input bias current Ib. Also calculate the value of the compensating resistance Rom to be connected in the non -inverting input to reduce the effect of input bias current. (741 Data sheet gives, Vj0 max = 6mV dc, Ib. max = 500 nA dc at Ta = 25 C )
13. A digital system has a 4-bit Input from 0000 to 1111. Draw the truth table of the \ v system which has high outputs when the equivalent decimal inputs are 1,2,3,7,8,9,10 y and 13. Draw the Karnaugh - Map for the truth table and obtain the simplified ( Boolean equation of the system.
14. A negative edge triggered J - K master - slave FLIP-FLOP has its J and K inputs tied to + Vcc- and a series of pulses (actually square waves) are applied to its clock input.
1. Draw the truth-table of the FLIP-FLOP.
2. If the FLIP-FLOP has a propagation delay of 50 ns, draw the input - output wave forms when the clock pulse has a frequency of 1 KHz. (Be sure to show the < propagation delay).
3. If the input clock pulse has a frequency of 1 MHz, what will be the frequency of the output pulse. ~
(2 x IQ 20 marks)
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