Analog Electronics

1. The early effect in a bipolar junction transistor is caused by

  1. fast turn-on
  2. fast turn-off
  3. large collector-base reverse bias
  4. large emitter-base forward bias

Correct answer: (C)
large collector-base reverse bias

2. MOSFET can be used as a

  1. current controlled capacitor
  2. voltage controlled capacitor
  3. current controlled inductor
  4. voltage controlled inductors

Correct answer: (B)
voltage controlled capacitor

3. Thermal runaway is not possible in FET because as the temperature of FET increases

  1. the mobility decreases
  2. the transconductance increases
  3. the drain current increases
  4. none of the above

Correct answer: (A)
the mobility decreases

4. A source follower using an FET usually has a voltage gain which is

  1. greater than +100
  2. slightly less than unity but positive
  3. exactly unity but negative
  4. about -10

Correct answer: (A)
greater than +100

5. A differential amplifier has a differential gain of 20,000 . CMRR=80 dB. The common mode gain is given by

  1. 2
  2. 1
  3. 43862
  4. 0

Correct answer: (A)

6. The approximate input impedance of the OPAMP circuit which has Ri=10k,Rf=100k,RL=10k

  1. 120k
  2. 110k
  3. 10k

Correct answer: (D)

7. An OPAMP has a slew rate of 5 V/μ S .The largest sine wave O/P voltage possible at a frequency of 1MHZ is

  1. 10 volts
  2. 5 volts
  3. 5/ volts
  4. 5/2 volts

Correct answer: (D)
5/2 volts

8. A change in the value of the emitter resistance Re in a differential amplifier

  1. affects the difference mode gain Ad
  2. affects the common mode gain Ac
  3. affects both Ad and Ac
  4. does not effect either Ad and Ac

Correct answer: (B)
affects the common mode gain Ac

9. A differential amplifier is invariably used in the i/p stage of all OP-AMPs.This is dome basically to provide the OP-AMPs with a very high

  1. CMRR
  2. bandwidth
  3. slew rate
  4. open-loop gain

Correct answer: (A)

10. The effective channel length of a MOSFET in a saturation decreases with increase in

  1. gate voltage
  2. drain voltage
  3. source voltage
  4. body voltage

Correct answer: (B)
drain voltage

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