Transistor Bias Configuration MCQ’s

This set of Analog Electronic Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Transistor Bias Configuration”.

1. For the given circuit, β = 150.


Fig. 1 has stability factor S1
If the above circuit is changed to below circuit


Fig. 2 having stability factor S2
Choose the correct option which is having better stability with S1 and S2 Values.
a) S2 = 151, S1 = 150. Circuit 1 has better stability
b) S2 = 100, S1 = 10 Circuit 2 has better stability
c) S2 = 151, S1 = 10.3 Circuit 1 has better stability
d) S2 = 151, S1 = 10.3 Circuit 2 has better stability

2. Consider the biasing circuit shown. The β for the circuit is large. R3 = 1kΩ, R4 = 2kΩ. The stability factor varies between 10 and 11. Find the maximum and minimum values of R2.


a) Minimum = 16.36kΩ, Maximum = 20kΩ
b) Minimum = 16.36kΩ, Maximum = 18kΩ
c) Minimum = 10 kΩ, Maximum = 20kΩ
d) Minimum = 6 kΩ, Maximum = 10kΩ

3. BJT is biased to _________
a) Work as a switch
b) Prevent thermal runaway
c) Increase DC collector current
d) Operate it in the saturation region

4. Choose the incorrect option according to self bias circuit?
a) Voltage gain increases
b) Stability factor is independent of collector resistance
c) BJT can be used in either of the three configurations
d) Excellent stability in collector current is achieved

5. Given Vout = 5V, β=100, I1=10mA, R1=100KΩ. Find the output resistance.


a) 8 kΩ
b) 8.163 kΩ
c) 7.582 kΩ
d) 8.4 kΩ

6. In the circuit given, the two Si transistors are similar. Given β=50, Vcc=12V, I1=5mA. Find I?


a) 5 mA
b) 4.807 mA
c) 4.5 mA
d) 5.2 mA

7. Why is self bias circuit not used in IC amplifier?
a) To reduce power losses
b) To reduce area used on the chip
c) Stability factor reduces in the IC
d) Voltage gain is reduced

8. Widlar current source was introduced to obtain a smaller output current.
a) True
b) False

9. Considering all transistors to be similar and β is very large, when I1 = 10 mA, find current I2.


a) 10 mA
b) 50 mA
c) 25 mA
d) 20 mA

10. Consider the following circuit, where the transistors are similar Si transistors. Given I1 = 2mA, I2 = 1μA, Vcc = 12 V, find R1 and R2.


a) R1 = 10kΩ, R2 = 6kΩ
b) R1 = 5.6kΩ, R2 = 20kΩ
c) R1 =18kΩ, R2 = any value
d) R1 = 18kΩ, R2 = 5.6kΩ

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