# Electronic Devices and Circuits Questions and Answers – High Frequency Response of Multistage Amplifiers

This set of Electronic Devices and Circuits Multiple Choice Questions & Answers (MCQs) focuses on “High Frequency Response of Multistage Amplifiers”.

1. What is the advantage of using a high frequency response of multistage amplifier?
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 amplifier does not provide suitable bandwidth or gain. To overcome this difficulty, we combine several amplification stages. The high frequency response of multistage amplifiers theory is used for high gain as well as high bandwidth.

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

Explanation: The high frequency response of multistage amplifiers 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 high frequency response of multistage amplifier if the gain of first stage is 4 and the gain of the second stage is 10?
a) 0.4
b) 4
c) 40
d) 2.5

Explanation: The total gain of a high frequency response of multistage amplifier 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.
Given, AV1 = 4 & AV2 = 10
AV = AV1 × AV2 = 4 × 10 = 40.

4. What is the total voltage gain of a high frequency response of multistage amplifier if input of first stage is 10V and the output of the second stage is 25V?
a) 0.4
b) 4
c) 40
d) 2.5

Explanation: The total gain of a high frequency response of multistage amplifier is the ration of the output of second stage amplifier to the input of first stage amplifier. Where, Voutput = 25V and Vinput = 10V.
AV = Voutput / Vinput = 25V / 10V = 2.5.

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 high frequency response of multistage amplifier?
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 high frequency response of multistage amplifier if the gain of first stage is 14dB, gain of the second stage is 12dB and gain of third stage is 24dB?
a) 40dB
b) 50.32dB
c) 50dB
d) 40.32dB

Explanation: The total gain of a high frequency response of multistage amplifier is the sum of the multiple stages when the gain is calculated is decibels. Given, AV1 = 14dB, AV2 = 12dB and AV3 = 24dB
AV = AV1 + AV2 + AV3 = 14dB + 12dB + 24dB = 50dB.

8. The coupling device is essential for a high frequency response of multistage amplifier.
a) True
b) False

Explanation: One of the main functions of the coupling device in a high frequency response of multistage amplifier 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. Which two terminals of the transistors are connected in high frequency response of multistage amplifier?
a) Collector
b) Base
c) Emitter
d) Collector, base and emitter

Explanation: The high frequency response of multistage amplifier circuit can be constructed by connecting the emitters of two consecutive transistors. A resistor is placed between each stage to act as a coupling device.

10. What are multistage amplifiers also known as?
a) Common collector amplifier
b) N – stage amplifier
c) Common base amplifier
d) Common emitter amplifier

Explanation: A single stage of amplifier provides an insufficient current gain or voltage gain. Several amplifier stages connected in cascade are used instead. Hence it is known as an n – stage cascading amplifier or multistage amplifier.

11. How many ports are there in a high frequency response of multistage amplifier?
a) 3
b) 4
c) 2
d) 5

Explanation: A high frequency response of multistage amplifier is a two – port network assembled from a series of amplifiers. Each amplifier directs its output to the input of the subsequent amplifier. The performance obtained from a single – stage amplifier is inadequate, therefore numerous stages are combined to form a multistage amplifier.

12. How is the voltage gain measured in a high frequency response of multistage amplifier?
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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