Linear Integrated Circuits (ECE) - May / June 2009 Question Papers

B.E. / B.Tech. DEGREE EXAMINATION, MAY/JUNE 2009

Fourth Semester

(Regulation 2004)

Electronics and Communication Engineering

Previous Year Question Paper

EC 1254 — LINEAR INTEGRATED CIRCUITS

(Common to B.E. (Part-Time) Third Semester Regulation 2005)

Time : Three hours

Maximum: 100 marks
Answer ALL questions.

PART A (10 x 2 = 20 marks)

1. Define the terms input bias current and input offset voltage.
2. Mention the characteristics of an ideal opamp.
3. Determine the output voltage Vo for the following circuit shown in figure.

4. Draw the circuit diagram of an opamp integrator. Why integrators are preferred over differentiators in analog computers?
5. What is a zero crossing detector?
6. Draw the basic functional diagram of a PLL circuit.
7. Find the resolution of a 12 bit DIA converter.
8. What is a Gilbert cell?
9. What are the requirements for designing a video amplifier?
10. What is a switched capacitor filter? Mention its applications.

PART B (5x 16 =8O marks)

11. (a) (i) Briefly explain the method of using constant current bias for
increasing CMRR in differential amplifier. (10)
. (ii) State the difference between constant current bias and current
mirror in differential amplifier. (6)

Or

(b) (i) Discuss frequency compensation in operational amplifier. (8)
(ii) Define slew rate and describe a method to improve slew rate. (8)

12. (a) (i) With diagram explain the principle of operation of triangular waveform generator using opamp. (10)
(ii) Design an opamp circuit to give an output voltage
V0 = 3V1 —2V2 + 5V3 where V1, V2 and V3 are inputs. (6)

Or

(b) (i) Design a second order low pass filter. (6)
(ii) Explain the working principle of Schmitt trigger. (10)

13. (a) (i) With block diagram explain how PLL can be used as frequency
multiplier circuit. (6)
(ii) Write a technical note on compander ICs. (10)

Or

(b) Explain the working principle of variable transconductance multiplier. (16)

14. (a) (i) With a neat diagram explain the working principle of successive
approximation type A/D converter. (10)
(ii) Discuss different types of analog switches. (6)

Or

(b) (i) Draw the circuit diagram of DIA converter 0800 and explain its
features. (8)
(ii) Discuss the functions of voltage to time converters. (8)

15. (a) Briefly explain the working principle of switch mode power supply with
necessary circuit diagram and waveforms.

Or

(b) With a functional diagram, explain the working principle of 8038 IC function generator.