Visvesvaraya Technological University (VTU) 2006 B.E Electrical and Electronics Engineering 5 th SME / OPERATIONAL AMPLIFIER AND LINEAR IC'S - Question Paper
Page No... 7
EE56
Fifth Semester B.E. Degree Examination, January/February 2006
t
Electrical & Electronics Engineering
Operational Amplifiers and Linear ICs
(Max.Marks : 100
Time: 3 hrs.)
Note: 7. Answer any FIVE full questions.
2. Use of resistor and capacitor standard values list and op-amp data sheets are permitted.
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1. (a) Sketch the circuit a high input impedance capacitor coupled non-inverting
amplifier. Briefly explain its operation. * (6 Marks)
(b) Briefly discuss the upper cutoff frequency of an op-amp circuit and show how the cutoff frequency can be set for inverting, non-inverting amplifiers. (8 Marks)
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(c) Using a 741 op - amp, design a high Zin non inverting amplifier to operate with a +36 V power supply. The load resistance is 12kCt. The lower cutoff frequency is to be 150Ez and the voltage gain is to be 7. (6 Marks)
2. (a) Sketch the circuit of a lag compensation network. Explain its operation and show
how it affects the frequency response of an operational amplifier. (6 Marks)
(b) Discuss the effects of stray capccitance on an op-amp circuit stability. Write the equations to determine the value of input stray capacitance that might produce circuit instability. (8 Marks)
(c) Determine the upper cutoff frequency for (i) a voltage follower using a 741 opamp and ii) a unity gain non-inverting amplifier using a 741 op-amp. Unity gain frequency for 741 op-amp is 800kHz.. * (6 Marks)
3. (a) Sketch an op-amp precision clamping circuit. Draw its input and output waveforms
and explain the circuit operation. _ (6 Marks)
(b) Show how a half wave precision rectifier can be combined with a summing circuit to produce a full wave precision rectifier. Draw the voltage waveforms at various stages of the circuit and write equations to show that full wave rectification is performed. (8 Marks)
(c) A 3.3kHz, 2V square wave with a 600H source resistance is to have its negative peak clamped at ground level. Using a bipolar op-amp, design a suitable precision clamping circuit. The tilt on the output-is not to exceed 2 percent. (6 Marks)
4. (a) Sketch the circuit of a capacitor coupled zero crossing detector. Show the
waveforms at various points in the circuit and explain its operation. (6 Marks)
(b) Draw the circuit of an op-amp astable multivibrator. Show the relevant voltage waveforms and explain its operation. (8 Marks)
(c) A capacitor coupled zero crossing detector is to provide an output voitage of approximately 17V, when a 3kHz12V square wave input is applied. Design a suitable circuit to use a bipolar op-amp. (6 Marks)
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5. (a) Sketch the circuit of a Triangular/Rectangular waveform generator. Draw the
output waveforms at different stages and explain the circuit operation. (6 Marks)
(b) Design a triangular/rectangular waveform generator to have an output frequency of 1 kHz, triangular output amplitude of 6V and square wave output amplitude of approximately 10V\ Use bipolar op-amps and estimate a minimum suitable op-amp slew rate. . . . (8 Marks)
(c) State Barkhausen criteria and explain how it is fulfilled in the phase shift oscillator. Write the equation for oscillation frequency in a phase shift oscillator. (6 Marks)
6. (a) Draw the circuits of second - order, low-pass and second order, high - pass active
filters. Sketch the frequency response for each circuit and briefly explain the operation of each filter. (12 Marks)
(b) Design a second - order, high - pass active filter to have a cutoff frequency of 12kHz. Use a 715 op-amp and estimate the highest signal frequency that will be passed. (8 Marks)
7. (a) Discuss the operation of a Voltage follower regulator, with a relevant circuit diagram.
(6 Marks)
(b) Sketch the circuit of a precision voltage regulator. Explain its operation and discuss how it differs from voltage follower regulators. (8 Marks)
(c) Explain the basic circuit of a 723 integrated circuit DC voltage regulator. (6 Marks)
8. Write explanatory notes with relevant circuit diagrams and waveforms, wherever applicapabie :
(a) Op-amp based circuit stability precautions
(b) Inverting Schmrtt trigger circuit and its I/O characteristic.
(c) Design of a Bandpass active filter
(d) Operation and applications of RLL (20 Marks)
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| Earning: Approval pending. |
