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Question Bank
Analog Integrated Electronics
1. Explain the virtual ground concept in op-amp and show the feasibiity
2. Define the term slew rate and also explain its significance in brief What are the different
compansation techniques and why they are used in op-amp?
3. Describe the first order model of the frequency response of op-amp and also find the gain using
small signal model.
4. Show the compansation analysis for the two stage op-amp.
5. Explain in detail the dominant pole compansation.
6. Give the significance of lead compansation and justify your talk.
7. Explain the frequecy response of internally compansation op-amp.
8. Write a short note on uncompansated op-amp.
9. Describe the telescopic op-amp with single ended output. How does it use the compansation in
op-amp.
10. Write a short notes on:
A) Single stage Op-amp
B) Multi Stage op-amp
11. An amplifier with a forward gain of A0 and two poles at 10 Mhz and 500 Mhz is placed in a unity
gain feedback loop. Calculate A0 for a phase argin of 600
12. Explain the multi pole system and give its relavance.
13. Explain the high frequency op-amp in detail.
14. A unity gain closed loop aplifier exhibits a frequency peaking of 50% in the vicinity of the gain
crossover. What is the phase margin.
15. Write the short note on
1. Integrater using op-amp
2.Differentiator using op-amp
3.Summing inverting and non-inverting op-amp
16. Consider a feedback amplifier for which the open-loop transfer function is given by
⎛
⎜
10
A=⎜
s
⎜
⎜1+ 4
⎝ 10
⎞
⎟
⎟
⎟
⎟
⎠
3
Let the feedback transfer function β be a constant independent of frequency. Find the frequency
w180(rad/s) at which the phase shift is 180o. Then, show that the feedback amplifier will be stable if the
feedback factor β is less than a critical value βcr and unstable if β>βcr, and find the value βcr .
17. An op-amp having a single-pole roll off at 100 Hz, and a low-frequency gain of 105 is operated is a
feedback loop with . β=.01
(a) What is the factor which feedback shifts the pole?
(b) To what frequency? I
(c) If β is changed to a value that results in a closed loop gain of +1, to what frequency does the pole
shift?
18. Consider an op-amp having a single-pole open-loop response with A0=105and an open-loop 3-dB
bandwidth 10 Hz. The amplifier is ideal otherwise. If the amplifier is connected in the non-inverting
configuration with a nominal low-frequency closed-loop gain of 100, find the frequency at which .|βA0|=1
Also, find the phase margin.
19. Consider an op-amp having a single-pole open-loop response with A0=105and an open-loop 3-dB
bandwidth 10 Hz. The amplifier is ideal otherwise. The amplifier is connected as a unity gain buffer. Find
the frequency at which |βA0|=1. Also, find the phase margin.
20. The open-loop voltage amplification of an amplifier is
A=
10 3
if ⎞
⎛
⎜1 + 5 ⎟
⎝ 10 ⎠
3
Find the phase and gain margins, and determine if the amplifier is stable if βv=.01 , and βv=.005. Give the
gain margin in dB.
21.An op-amp has open-loop phase and gain characteristics shown below. The opamp is used as a noninverting amplifier. Use the graphical subtraction technique and determine is the amplifier is stable if at
gains of (a) 10,000, (b), 1,000, and (c) 10. If the amplifier is stable at a particular gain, give the gain- and
phase margins.
22.The Bode plots of the figure below describe the open-loop gain of an op-amp. Find gain- and phase
margins of a noninverting amplifier feedback amplifier using this op amp when
(a) β=.00179
(b)β=.0316
(c)β=.1778
23.The figure below show the loop gain of a feedback amplifier of an op amp.
(a) How much must the loop gain be reduces to just make the amplifier stable?
(b) Estimate the reduction in loop gain to make the amplifier stable with a 450phase margin
24.The open-loop low-frequency gain of f=104hz an op-amp is 100 dB. At a frequency of the magnitude of
the open-loop gain is 38dB. The op-amp has a dominant-pole open-loop response. Determine the
frequency of the dominant pole and the unity-gain bandwidth.
25.The open-loop low-frequency gain of f=104hz an op-amp is 100 dB. At a frequency of the magnitude of
the open-loop gain is 38 dB. The op-amp has a dominant-pole open-loop response. Determine the
frequency of the dominant pole and the unity-gain bandwidth.
26.An amplifier with a forward gain of A0 has two coincident poles at wp. Calculate the axium value of A0
for a 600 phase argin with closed loop gain of unity and 4.
27. An aplifier has a forward gain of A0=1000 and two poles at wp1 and wp2. For wp1=1Mhz, calculate he
PM of a unity gain feedback loop if wp2=2wp1.
28. Explain the slewing in two stage op-amp with suitable diagras
29. Write the short note on-
•
•
Positive Slewing
Negative Slewing
30. Explain the compensation technique using common gate stage and draw the equivalent circuit.