# Cascode and Darlington Amplifier MCQ’s

This set of Analog Electronic Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Cascode and Darlington Amplifier”.

1. Consider the circuit shown below where hfe=50.

Calculate the input resistance of the network.
a) 255 kΩ
b) 13 MΩ
c) 5 MΩ
d) 250 kΩ

2. Given the following circuit.

It is given that hfe=55, hie=1kΩ, hoe=25μΩ-1. Calculate the net current gain and the voltage gain of the network.
a) AI=192.6, Av=220
b) AI=1, AV=220
c) AI=192.6, AV=1
d) AI=192.6, AV=55

3. Which of these are incorrect about Darlington amplifier?
a) It has a high input resistance
b) The output resistance is low
c) It has a unity voltage gain
d) It is a current buffer

4. In a Darlington pair, the overall β=15000.β1=100. Calculate the collector current for Q2 given base current for Q1 is 20 μA.

a) 300 mA
b) 298 mA
c) 2 mA
d) 200mA

5. What is the need for bootstrap biasing?
a) To prevent a decrease in the gain of network
b) To prevent an increase in the input resistance due to the biasing network
c) To prevent a decrease in the input resistance due to the presence of multiple BJT amplifiers
d) To prevent a decrease in the input resistance due to the biasing network

6. What is a cascade amplifier?
a) A cascade of two CE amplifiers
b) A cascade of two CB amplifiers
c) A cascade of CE and CB amplifiers
d) A cascade of CB and CC amplifiers

7. Darlington amplifier is an emitter follower.
a) True
b) False

8. Consider a Darlington amplifier. In the self bias network, the biasing resistances are 220kΩ and 400 kΩ. What can be the correct value of input resistance if hfe = 50 and emitter resistance = 10kΩ.
a) 141 kΩ
b) 15 MΩ
c) 20 MΩ
d) 200 kΩ

9. Consider the figure shown.

Given that gm1 = 30mΩ-1 and gm2 = 50mΩ-1, α1 = 1.1, α2 = 1.5 what is the transconductance of the entire network?
a) 80 mΩ-1
b) 75 mΩ-1
c) 33 mΩ-1
d) 55 mΩ-1

10. In the given circuit, hfe = 50 and hie = 1000Ω, find overall input and output resistance.

a) RI=956Ω, RO=1.6 kΩ
b) RI=956 kΩ, RO=2 kΩ
c) RI=956 Ω, RO=2 kΩ
d) RI=900Ω, RO=10 kΩ

11. Find the transconductance of the network given below, provided that gm1 = 30mΩ-1. VT = 25mV, VBias > 4V.

a) 30mΩ-1
b) 10mΩ-1
c) 1mΩ-1
d) 20mΩ-1 5 Star
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