# Electronic Devices and Circuits Questions and Answers – The Cascode Transistor Configuration

This set of Electronic Devices and Circuits Multiple Choice Questions & Answers (MCQs) focuses on “The Cascode Transistor Configuration”.

a) High gain and high bandwidth
b) High gain and low bandwidth
c) Low gain and high bandwidth
d) Low gain and low bandwidth

Explanation: A circuit having a single transistor configuration does not provide suitable bandwidth or gain. To overcome this difficulty, we combine several amplification stages. The cascading transistor configuration theory is used for high gain as well as high bandwidth.

2. What is the advantage of using CB amplifier configuration in a cascading transistor configuration?
a) High efficiency
b) Low distortion
c) Good high frequency operation
d) Good low frequency operation

Explanation: The cascading transistor configuration circuit can be constructed with two configurations of a transistor that is CE (common-emitter) and CB (common base). The CB (common base) configuration delivers a good high-frequency operation.

3. What is the total voltage gain of a cascading transistor configuration if the gain of first stage is 48 and the gain of the second stage is 12?
a) 6.75
b) 6.55
c) 5.76
d) 5.65

Explanation: The total gain of a cascading transistor configuration can be calculated by the formula given below. Where, AV = overall gain, AV1 = voltage gain of first stage and AV2 = voltage gain of second stage.
AV = AV1 × AV2 = 4.8 × 1.2 = 5.76.

4. What is the total voltage gain of a cascading transistor configuration if input of first stage is 50V and the output of the second stage is 100V?
a) 20
b) 0.2
c) 2.5
d) 2

Explanation: The total gain of a cascading transistor configuration is the ration of the output of second stage amplifier to the input of first stage amplifier. Where, Voutput = 100V and Vinput = 50V.
AV = Voutput / Vinput = 100V / 50V = 2.

5. What does cascading of two transistor amplifiers imply?
a) Output of first stage sent to input of second stage
b) Output of first stage sent to coupling device
c) Input of first stage sent to input of second stage
d) Not related

Explanation: In multi-stage amplifiers, the output of first stage is coupled to the input of second stage using a coupling device. The coupling devices is typically a capacitor or a transformer. Cascading is known as the process of combining two amplifier stages using a coupling device.
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6. How many methods of coupling are used for a cascading transistor configuration?
a) 3
b) 4
c) 2
d) 5

Explanation: There are four types of coupling mechanisms used. They are Resistance-capacitance coupling, thermal coupling, impedance coupling and transformer coupling. Resistance-capacitance coupling is the most vastly used mechanism.

7. What is the total voltage gain of a cascading transistor configuration if the gain of first stage is 10dB, gain of the second stage is 20dB and gain of third stage is 30dB?
a) 60.32dB
b) 50dB
c) 60dB
d) 50.32dB

Explanation: The total gain of a cascading transistor configuration is the sum of the multiple stages when the gain is calculated is decibels. Given, AV1 = 10dB, AV2 = 20dB and AV3 = 30dB
AV = AV1 + AV2 + AV3 = 10dB + 20dB + 30dB = 60dB.

8. The coupling device is essential for a cascading transistor configuration.
a) True
b) False

Explanation: One of the main functions of the coupling device in a cascading transistor configuration is to block the direct current from passing through to the input of next stage from the output of the first stage. Another function of the coupling device is to transfer the current from the output of first stage to the input of the second stage.

9. What is the purpose of using a cascading transistor configuration?
a) Increase voltage gain
b) Decrease voltage gain
c) Increase current gain
d) Decrease current gain

Explanation: A circuit having a single transistor configuration does not provide suitable bandwidth or gain. The purpose of a cascading transistor configuration is to provide an increase in the voltage gain. The total gain of a cascading transistor configuration is the product of the voltage gains of the discrete stages.

10. How is the voltage gain measured in a cascading transistor configuration?
a) Volts
b) Ampere
c) Decibels
d) Dimensionless

Explanation: The voltage gain is measured in terms of decibels. The total voltage gain is calculated as the product of individual stages or as a sum of all the stages if the gain calculated at each intermediate stage was measured in decibels as well.

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