GATE ECE topic:bjt-mosfet-amplifiers PYQs & Answers — Page 3

Questions 21–30 of 33. Imported answers require independent review unless marked reviewed.

In the circuit shown, the threshold voltages of the pMOS (

) and nMOS (

) transistors are both equal to 1 V. All the transistors have the same output resistance

of 6 M

. The other parameters are listed below:

and

are the carrier mobilities, and

is the oxide capacitance per unit area. Ignoring the effect of channel length modulation and body bias, the gain of the circuit is ____ (rounded off to 1 decimal place).

Diagram for Electronics and Communication Engineering question 54

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Two identical MOS transistors M₁ and M₂ are connected as shown below. The circuit is used as an amplifier with the input connected between G and S terminals and the output taken between D and S terminals. V_bias and V_D are so adjusted that both transistors are in saturation. The transconductance of this combination is defined as

while the output resistance is

, where i_D is the current flowing into the drain of M₂. Let g_m₁, g_m₂ be the transconductances and r_o₁, r_o₂ be the output resistances of transistors M₁ and M₂, respectively.

Diagram for Electronics and Communication Engineering question 1

Which of the following statements about estimates for g_m and r_o is correct?

Your answerChoose one option.

and

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An n-channel enhancement mode MOSFET is biased at

and

, where

is the gate-to-source voltage,

is the drain-to-source voltage and

is the threshold voltage. Considering channel length modulation effect to be significant, the MOSFET behaves as a

Your answerChoose one option.

voltage source with zero output impedance

voltage source with non-zero output impedance

current source with finite output impedance

current source with infinite output impedance

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bipolar junction transistor (BJT) is operating in the active region. If the reverse bias across the base-collector junction is increased, then

Your answerChoose one option.

the effective base width increases and common-emitter current gain increases

the effective base width increases and common-emitter current gain decreases

the effective base width decreases and common-emitter current gain increases

the effective base width decreases and common-emitter current gain decreases

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Consider an

-channel MOSFET having width

, length

, electron mobility in the channel

and oxide capacitance per unit area

. If gate-to-source voltage

, drain-to-source voltage

, threshold voltage

and

, then transconductance

(in mA/V) is _____.

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A good transconductance amplifier should have

Your answerChoose one option.

high input resistance and low output resistance

low input resistance and high output resistance

high input and output resistances

low input and output resistances

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The Miller effect in the context of a Common Emitter amplifier explains

Your answerChoose one option.

an increase in the low-frequency cutoff frequency

an increase in the high-frequency cutoff frequency

a decrease in the low-frequency cutoff frequency

a decrease in the high-frequency cutoff frequency

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Consider the circuit shown in the figure. Assume base-to-emitter voltage

and common-base current gain

of the transistor is unity.

Diagram for Electronics and Communication Engineering question 14

The value of the collector-to-emitter voltage

(in volt) is _____.

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Two

-channel MOSFETs, T1 and T2, are identical in all respects except that the width of T2 is double that of T1. Both the transistors are biased in the saturation region of operation, but the gate overdrive voltage (

) of T2 is double that of T1, where

and

are the gate-to-source voltage and threshold voltage of the transistors, respectively. If the drain current and transconductance of T1 are

and

, respectively, the corresponding values of these two parameters for T2 are

Your answerChoose one option.

and

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Assuming that transistors M1 and M2 are identical and have a threshold voltage of 1 V, the state of transistors M1 and M2 are respectively

Diagram for Electronics and Communication Engineering question 40

Your answerChoose one option.

Saturation, Saturation

Linear, Linear

Linear, Saturation

Saturation, Linear

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GATE ECE topic:bjt-mosfet-amplifiers PYQs

Question 54

Question 1

Question 9

Question 10

Question 11

Question 13

Question 14

Question 14

Question 38

Question 40