MCQ for unit 5 OF NEC-409 Analog & Digital Electronics

1. NEC-409: ANALOG AND DIGITAL ELECTRONICS
MCQ for unit 5
1. An ideal OPAMP is an ideal
a. Current controlled Current source
b. Current controlled Voltage source
c. Voltage controlled Voltage source
d. Voltage controlled Current source
2. A 741Type OPAMP
has a gain bandwidth product of 1MHz. A noninverting amplifier using this opamp & having a voltage
gain of 20db will exhibit3db bandwidth of
a. 50KHz
b. 100KHz
c. 1000/17KHz
d. 1000/7.07KHz
3. An amplifier using an opamp with slew rate SR = 1v/sec has a gain of 40db. If this amplifier has to
faithfully amplify sinusoidal signals from dc to 20KHz without introducing any slewrate
induced distortion, then the input signal level exceed
a. 795mV
b. 395mV
c. 795mV
d. 39.5mV
4. The ideal OPAMP has the following characteristics
a. Ri = ∞ A = ∞ R0 = 0
b. Ri = 0, A = ∞ R0 = 0
c. Ri = ∞ A = ∞ R0 = ∞
d. Ri = 0, A = ∞ R0 = ∞
5. The approximate input impedance of the opamp circuit which has Ri = 10k, Rf = 100k, RL = 10k
a. ∞
b. 120k
c. 110k
d. 10k
6. An opamp has a slew rate of 5V/S. The largest sine wave o/p voltage possible at a frequency of 1MHz
is
a. 10 V
b. 5 V
c. 5V
d. 5/2 V
7. Assume that the opamp of the fig. Is ideal. If Vi is a triangular wave, then V0 will be
a. square wave
b. Triangular wave

2. c. Parabolic wave
d. Sine wave
8. A differential amplifier is invariably used in the i/p stage of all opamps. This is done basically to
provide the opamps with a very high
a. CMMR
b. bandwidth
c. slew rate
d. openloop gain
9. A differential amplifier has a differential gain of 20, 000. CMMR = 80dB. The common mode gain is
given by
a. 2
b. 1
c. ½
d. 0
10. In the differential voltage gain & the common mode voltage gain of a differential amplifier are 48db
& 2db respectively, then its common mode rejection ratio is
a. 23dB
b. 25dB
c. 46dB
d. 50dB
11. Which circuit converts irregularly shaped waveform to regular shaped waveforms?
a) Schmitt trigger
b) Voltage limiter
c) Comparator
d) None of the mentioned
12. Determine the upper and lower threshold voltage
a) V = +14.63v, V = +14.63v
b) V = 14.63v,V = 14.63v
c) V = V = ±14.63v
d) None of the mentioned
13. What happens if the threshold voltages are made longer than the noise voltages in schmitt trigger?
a) All the mentioned
b) Enhance the output signal
c) Reduce the transition effect
d) Eliminate false output transition

3. 14. To a schmitt trigger in noninverting configuration an input triangular wave of 1V is applied. What
will be the output waveform, if the upper and lower threshold voltages are 0.25v?
a) Square waveform
b) Pulse waveform
c) Sawtooth waveform
d) Cannot be determined.
15. In which configuration a dead band condition occurs in schmitt trigger
a) Differential amplifier with positive feedback
b) Voltage follower with positive feedback
c) Comparator with positive feedback
d) None of the mentioned
16. Calculate the hysteresis voltage for the schmitt trigger from the given specification:
R =56kΩ , R = 100Ω ,V = 0v & V = ±14v.
a) 0 mv
b) 25 mv
c) 50 mv
d) 25mv
17. How to limit the output voltage swing only to positive direction?
a) Combination of two zener diodes
b) Combination of zener and rectifier diode
c) All of the mentioned
d) Combination of two rectifier diodes
18. For the circuit shown below, obtain output waveform. Assume zener voltage to be 4.78v and voltage
drop across the forward biased zener to be 0.7v.

4. 19. A basic opamp circuit has a zener and rectifier diode connected in the feedback path. Calculate the
maximum positive voltage. Where, zener voltage = 5.1 v and voltage drop across the forward biased
zener = 0.7v?
a) V = 5.8v
b) V = 9.9v
c) V = 4.7v
d) V = 7.1v
20. Use the specification and obtain the output voltage swing for opamp comparator.
Specification: R= 1kΩ; R =10kΩ; V =6v; V =±15v (Assume forward bias of zener = 0.7v).

5. 21. Type of memory which is used to read data but not to write on it is classified as
A. random only memory.
B. read access memory.
C. read only memory.
D. random access memory.
22. Specific type of memory that can be erased anytime is classified as
A. BROM.
B. DROM.
C. EPROM.
D. EROM.
23 An access store from which data can be read and can be written on it, this storage is classified as
A. read only memory.
B. random access memory.
C. random only memory.
D. read access memory.
24. All new programs that are written on erasable programmable read only memory are classified as
A. EPROM programmer.
B. EROM programmer.
C. PROM programmer.
D. DROM programmer.
25. Type of ROM which is manufactured without any initial storage in it is called
A. PROM.
B. EROM.
C. BROM.
D. DROM.