Visvesvaraya Technological University (VTU) 2006 B.E Fifth Semester , Operational Amplifier and Linear IC’s - Question Paper

Fifth Semester B.E. Degree exam , July 2006
Electrical and Electronics Engineering
Operational Amplifier and Linear IC’s
Time:3 hrs] [Max.Marks:100
Note: 1. ans any 5 full ques..
2. presume suitable data wherever needed.
1. a. Design a high Zin capacitor coupled voltage follower. Show that the input
impedance is very large compared to the capacitor coupled voltage follower. ( 06 Marks)
b. Design a capacitor coupled inverting amplifier using 741 with a gain of 50
and the output amplitude is 2.5 volts. The signal frequency range is 10Hz to
1 KHz. The load resistance is 250 ohms. (08 Marks)
c. A difference amplifier has the subsequent components, R1= R2= 6.8 KW ,
R3 = 68 KW, Load R L = 1.5 KW, Input capacitors C1 = one mfd. Determine the
Circuit lower cut off frequency and the maximum differential input voltage
if the output amplitude is not to exceed five volts. (06 Marks)
2. a. elaborate the causes of circuit instability? List the precautions to be taken for
circuit stability.
b. discuss the frequency compensating methods adopted to stabilize the opamp
circuits. (06 Marks)
c. A 741 with a slew rate of 0.5 v/msec is used as a voltage follower,
i) compute the slew rate limited cut off frequency if the sine wave output
is five volts.
ii) If this circuit is to operate with a unity gain cut off frequency of 800 KHZ,
compute the maximum peak value of the sinusoidal output voltage,
iii) If the upper cut off frequency is eight KHz, compute the maximum value of the
peak output voltage. (06 Marks)
3. a. With a neat circuit diagram discuss the working of a precision full wave rectifier
with relevant waveforms. (08 Marks)
b. discuss the working of a precision clamping circuit with a neat circuit diagram and
relevant waveforms. (06 Marks)
c. With a neat circuit diagram and relevant waveforms discuss the working of a voltage
follower peak detector. (06 Marks)
4. a. discuss the working of a capacitor coupled crossing detector with a neat circuit
diagram and relevant waveforms. (06 Marks)
b. discuss the input / output characteristics of a inverting Schmitt trigger circuit using
opamp
(08 Marks)
c. discuss how variable UTP and LTP are adjusted in an inverting Schmitt trigger
with a neat circuit diagram and relevant wave forms. (06 Marks)
5. a. With a neat circuit diagram and relevant waveforms discuss the working of a triangular/
rectangular waveform generator using opamps.
(08 Marks)
b. With a neat circuit diagram discuss the working of a RC phase shift oscillator using
opamp.
(06 Marks)
c. Design a RC phase shift oscillator using 741 and a supply of ± 12 volts to generate an
output frequency of 3.5 KHz. (06 Marks)
6. a. What is the difference ranging from active and passive filters? What is significance of the
order of the filter? discuss the terms high pass filter, low pass filter, band pass filter
and band stop filter. (10 Marks)
b. discuss the terms phase lag circuit and phase lead circuit with reference to an all pass
filter
c. Design a 1st order LPF using opamp
for a cut off frequency of one KHz. (04 Marks)
7. a. With a block diagram discuss the working of a PLL. (06 Marks)
b. discuss the terms line regulation and load regulation for a dc voltage regulator. (06 Marks)
c. With a neat diagram discuss the working of a precision voltage regulator. (08 Marks)
8. Write short notes on:
a. Use of single polarity supply in opamps
b. Sample and hold circuit.
c. Astable multivibrator.
d. Wein bridge oscillator.

Earning:   Approval pending.