# Electronic Devices and Circuits Questions and Answers – N-Stage Cascading Amplifiers

This set of Electronic Devices and Circuits Multiple Choice Questions & Answers (MCQs) focuses on “N-Stage Cascading Amplifiers”.

1. What is the purpose of using ann-stage cascading transistor amplifier?
a) Increase voltage gain
b) Decrease voltage gain
c) Increase current gain
d) Decrease current gain

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

2. Which two terminals of the transistors are connected in an n-stage cascading amplifier?
a) Collector
b) Base
c) Emitter
d) Collector, base and emitter

Explanation: The n-stage cascading transistor 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.

3. What is the total voltage gain of a cascading transistor amplifier if the individual gains are: 1.5, 2.3, 3.46 and 2?
a) 18.52
b) 9.26
c) 23.87
d) 11.26

Explanation: The total gain of a cascading transistor amplifier can be calculated by taking the product of the individual stages. Where,
AV = AV1 × AV2 × AV3 × AV4 = 1.5 × 2.3 × 3.46 × 2 = 23.87

4. What is the total voltage gain of the nth stage in an n-stage cascading amplifier?
a) AVK = AIK × RLK × RiK
b) AVK = AIK × RiK / RLK
c) AVK = AIK / RLK × RiK
d) AVK = AIK × RLK / RiK

Explanation: The gain for any intermediate stage in an n-stage cascading amplifier can be calculated using AVK = AIK × RLK / RiK. Where, AIK, RLK and RiK is the estimated with respect to the values of the previous stages. AIK represents the voltage gain while RLK and RiK represent the effective load impedance.

5. What are n-stage cascading amplifiers also known as?
a) Common collector amplifier
b) Multistage amplifiers
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 of multistage amplifier.
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6. How many ports are there in an n-stage cascading amplifier?
a) 3
b) 4
c) 2
d) 5

Explanation: An n-stage cascading 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, there fore numerous stages are combined to form a multistage amplifier.

7. What is the total voltage gain of an n-stage cascading amplifier if the gain of stages are 5dB, 14dB, 20dB, 15dB and 24dB?
a) 76dB
b) 46dB
c) 78dB
d) 79dB

Explanation: The total gain of ann-stage cascading amplifier is the sum of the gain measured at each stage only when the gain is calculated is decibels. Given, AV1 = 5dB, AV2 = 14dB, AV3 = 20dB, AV4 = 15dB and AV5 = 24dB
AV = AV1 + AV2 + AV3 + AV4 + AV5 = 5dB + 14dB + 20dB + 15dB + 24dB = 78dB

8. The middle stage of an n-stage cascading amplifier provides most gain.
a) True
b) False

Explanation: The middle stage of an n-stage cascading amplifier provides most gain. It provides the maximum voltage gain along with fluctuating the DC level of the signal. It also converts the signal from one mode to another while processing.

9. At what frequencies does the gain of the n-stage cascading amplifier get compromised?
a) Mid-range frequencies
b) High-range frequencies
c) Low-range frequencies
d) It does not affect the gain

Explanation: Multistage cascading amplifiers or n-stage cascading amplifiers have a low cut off frequency. The gain of the system is compromised at lower frequencies. To calculate the cut off frequency fc = f1 / √(21/n – 1), where f1 is initial frequency.

10. How is the voltage gain measured in an n-stage cascading 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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