SRM INSTITUTE OF SCIENCE AND TECHNOLOGY, RAMAPURAM
FACULTY OF ENGINEERING AND TECHNOLOGY
DEPARTMENT OF ELECTRONICS AND COMMUNICATION
18CSS201J-ANALOG AND DIGITAL ELECTRONICS
QUESTION BANK – UNIT -1
Part – A (Each Question Carries 1 mark)
1.BJT is a __________ controlled device .
a.Voltage (b) Current (c) Resistance (d) Impedance
ANS: b. Current
2.The transistor is said to be in the ......... when both the junctions are forward biased
a. Active region b. Passive region c. Cut off region d. Saturation region
ANS:d. Saturation region
3.Transistor works as an open switch when emitter junction is.......biased and collector junction
is......biased
a. Forward, forward b. Reverse, reverse c. Reverse, forward d. Forward, reverse
ANS: b. Reverse, reverse
4.In a BJT
A.The base region is sandwiched between emitter and collector
B.The collector is sandwiched between base and emitter
C.The emitter regionis sandwiched between base and collector
D.None of the above
ANS: A.The base region is sandwiched between emitter and collector
5. Output of a FET will be controlled by ____________ at input.
(a)Voltage (b) Current (c) Electric field (d) Potential Difference
ANS: C. Electric Field
6.Amplifiers and oscillators using BJT, operate in ...... region
A.Inverted mode
B.Active
C.Cut off
D.Saturation
ANS: B.Active
7. In saturation region FET will be acting as a
a. Constant current source b. Constant voltage source c.Linear resistor d.capacitor
SRM INSTITUTE OF SCIENCE AND TECHNOLOGY, RAMAPURAM
FACULTY OF ENGINEERING AND TECHNOLOGY
DEPARTMENT OF ELECTRONICS AND COMMUNICATION
ANS:a. Constant current source
8. Between the peak point and the valley point of UJT emitter characteristics we have
………….. region
a.Saturation b.Negative resistance c.Cut-off d. active
ANS. b
9.The relationship between input voltage and output voltage by keeping input current constant is
known as
A. Input Characteristics B. Output Characteristics C. Trans-resistance D. Trans-conductance
ANS: B
10.For an Op-amp with negative feedback, the output is …….
a. Equal to the input b. Increased
c.Fed back to the inverting input d.fed back to the noninverting input
ANSWER: c
11.A certain noninverting amplifier has Ri of 1 kΩ and Rf of 100 kΩ. The closed-loop voltage
gain is ………
a.100,000 b.1000 c.101 d.100
ANS: C
12. Depending on the value of input and reference voltage a comparator can be named as
a) Voltage follower b) Digital to analog converter
c) Schmitt trigger d) Voltage level detector
ANS: d. Voltage detector
13. Power amplifier directly amplifies ___________
a) Voltage of signal
b) Current of the signal
c) Power of the signal
d) All of the mentioned
ANS: d
14.This is an example of the output swing for a class ________ amplifier.
SRM INSTITUTE OF SCIENCE AND TECHNOLOGY, RAMAPURAM
FACULTY OF ENGINEERING AND TECHNOLOGY
DEPARTMENT OF ELECTRONICS AND COMMUNICATION
a. A b. B c. AB d. C
ANS: b. B
15. Class ________ amplifiers are normally operated in a push-pull configuration in order to
produce an output that is a replica of the input.
a. A b.B c.AB d.C
ANS: AB
16. An oscillator converts ……………..
a. ac power into dc. Power b. dc power into ac power
c.mechanical power into a.c. power d. none of the above
ANS: b. dc power into ac power
17. A UJT has ___________.
a. Two pn junctions b. One pn junction
c. Three pn junctions d. Any number of junctions
ANS: b. One p n junction
18.The standard 555 timer package includes
a.2 b.10 c.12 d.25
ANS: d.25
19. 1. The function of Pin 3 in 555 timer is:
a. control voltage b. discharge c. output d. Reset
ANS: C.output
20. Which of the following is not a characteristic of crystal oscillator?
a) Highly stable with time b) Highly stable with temperature
c) Highly selective d) Frequency depends external resistors and capacitors
ANS: d. Frequency depends external resistors and capacitors
PART – B (Each question carries 4 marks)
21.In a certain transistor, collector current is 0.98 and base current is 20Ma. Determine the value
of α.
A. 98
B. 0.98
C. 0.098
D. 980
ANSWER: B
22. 3.Which of the following is true for the cut-off region in an npn transistor
SRM INSTITUTE OF SCIENCE AND TECHNOLOGY, RAMAPURAM
FACULTY OF ENGINEERING AND TECHNOLOGY
DEPARTMENT OF ELECTRONICS AND COMMUNICATION
A. Potential Difference between emitter and the base is smaller than 0.5V
B. Potential Difference between emitter and the base is smaller than 0.4V
C. The collector current is always zero and the base current is always non- zero
D. Collector current increases with the increase in base current
ANSWER: B
23. In the circuit shown below R2 = 42 kΩ. Assume that the op-amp is ideal. Determine the value
of R1 so that the magnitude of closed-loop gain, G = vO / vS is 14.
A. 3KΩ B.4 KΩ C.5 KΩ D. KΩ
ANS. A . 3KΩ
24. A certain OP-amp has bias currents of 50 μA. The input offset current is ……..
a.700 nA b.99.3 μA c.49.7 μA d. 99.3Na
ANS: A. 700Na
25. The output of a particular Op-amp increases 8V in 12μs. The slew rate is …….
a. 90 V/μs b. 0.67 V/μs c. 1.5 V/μs d. 0.5V/ μs
ANS: b. 0.67 V/μs
26. A certain noninverting amplifier has Ri of 1 kΩ and Rf of 100 kΩ. The closed-loop voltage
gain is ………
a.100,000 b.1000 c.101 d.100
Ans: 101
27. n a UJT, with Vnn as the voltage across two base terminals, the emitter potential at peak point
is given by:
a.VBB b. V0 c. Vnn + VD d. Vnn - VD
ANS:C. Vnn + VD
28.What does the discharge transistor do in the 555 timer circuit?
a. charge the external capacitor to stop the timing
b charge the external capacitor to start the timing over again
SRM INSTITUTE OF SCIENCE AND TECHNOLOGY, RAMAPURAM
FACULTY OF ENGINEERING AND TECHNOLOGY
DEPARTMENT OF ELECTRONICS AND COMMUNICATION
c. discharge the external capacitor to stop the timing
d
discharge the external capacitor to start the timing over again
.
ANS: d. discharge the external capacitor to start the timing over again
29.In class B operation, at what fraction of VCC should the level of VL(p) be to
achieve the maximum power dissipated by the output transistor?
a. 0.5 b. 0.636 c. 0.707 d. 1
ANS:
B
30. The ‘Pinch – off’ voltage of a JFET is 5.0 volts. Its ‘cut – off’ voltage is
a. (5.0)1/2 V (b)2.5 V (c) 5.0 V d. (5.0)3/2 V
ANS: C 5.0 V
PART – C (Each Question Carries 12 Marks)
31. From the given circuit, using a silicon transistor, what is the value of IBQ and
VCE?
a) 47.08 mA and 0.683 V
b) 47.08 Ua and 6.83 V
c) 50 uA and 68.3V
d) 0 mA and 0V
ANS:B 47.08 Ua and 6.83 V
32. A transistor is connected in common emitter configuration as shown in figure. Collector
supply voltage Vcc is 10V, load resistance RL is 800Ω, voltage drop across the load resistance is
SRM INSTITUTE OF SCIENCE AND TECHNOLOGY, RAMAPURAM
FACULTY OF ENGINEERING AND TECHNOLOGY
DEPARTMENT OF ELECTRONICS AND COMMUNICATION
0.8V and current gain α=0.96. Determine the collector emitter voltage and base current.
a.VCE = 9.2V IB= 41.67 µA
b. VCE = 0.92V IB= 41.67 µA
c. VCE = 9.2V IB= 4.167 µA
d. VCE = 92V IB= 41.67 µA
ANS:a VCE = 9.2V IB= 41.67 µA
33. An N- channel JFET has IDSS = 10mA and Vp = -4V.Determine the minimum value of VDSS
for pinch off region and drain current ID for VGS = -2V in pinch off region.
a. VDS= -4V
b. VDS= -5V
c. VDS=-6 v
d. VDS= 0V
ANS:a VDS= -4V
34. A JFET amplifier with stabilized biasing circuit shown in the figure has device parametrs
Vp= -2V , IDSS = 5mA,RL= 910Ω,: RF = 2.29 K Ω, R1= 12 MΩ, R2 = 8.57 M Ω VDD=24 V.Find
the value od drain current ID at the operating point.
a. 4.274 mA
b.0.46 mA
SRM INSTITUTE OF SCIENCE AND TECHNOLOGY, RAMAPURAM
FACULTY OF ENGINEERING AND TECHNOLOGY
DEPARTMENT OF ELECTRONICS AND COMMUNICATION
c.42.74 mA
d.427.4 mA
ANS: a. 4.274 mA
35. For the ideal op amp shown, what should be the value of resistor Rf to obtain a gain of 5?
a. 12.0 kΩ
b. 19.5 kΩ
c. 22.5 kΩ
d.27.0 kΩ
ANS:b 19.5 kΩ
36. For the difference amplifier circuit shown, determine the output voltage at terminal A.
a. - 18.13 V
SRM INSTITUTE OF SCIENCE AND TECHNOLOGY, RAMAPURAM
FACULTY OF ENGINEERING AND TECHNOLOGY
DEPARTMENT OF ELECTRONICS AND COMMUNICATION
b. -6.07 V
c. 6.07 V
d.15.45 V
ANS: a. - 18.13 V
