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Electronics and Communication Engineering

GATE ECE BJT and MOSFET amplifiers PYQs

Build your understanding with focused practice from past exam papers.

How to practice BJT and MOSFET amplifiers

Attempt a question, record the concept and assumptions, then check the available answer. Rework mistakes after revising the relevant concepts. Topic tags can overlap; review the question context.

GATE ECE syllabus

Questions 1–10 of 33. Imported answers require independent review unless marked reviewed.

Topic practice 33 questionsPage 1 of 4

Question 18

Open question
ECMCQ1 markNeeds review
Consider the circuit shown in the Figure with

and

.
Assume

and

for the BJT.
Which of the following options is the correct value of the current

?
Diagram for Electronics and Communication Engineering question 18

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Question 29

Open question
ECMSQ1 markNeeds review
Figure shows the output characteristics of two different Bipolar Junction Transistors (BJT), BJT 1 with magnitude of Early voltage

, and BJT 2 with magnitude of Early voltage

. Which of the following options is/are correct regarding the Early voltages?
Diagram for Electronics and Communication Engineering question 29

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Question 50

Open question
ECMCQ2 marksNeeds review
A small signal source,

is applied to a BJT circuit as shown in the Figure.
Assume zero source resistance,

V,

, Early voltage = 100 V and Thermal voltage = 25 mV. Effect of internal parasitic capacitances of the BJT may be neglected.
Which expression is the best approximation of the output voltage

?
Diagram for Electronics and Communication Engineering question 50

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Question 21

Open question
ECMCQ1 markNeeds review
A simplified small-signal equivalent circuit of a BJT-based amplifier is given below. The small-signal voltage gain

(in V/V) is ________.
Diagram for Electronics and Communication Engineering question 21

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Question 22

Open question
ECMCQ1 markNeeds review
The ideal BJT in the circuit given below is biased in the active region with a

of 100. If

is 10

A, then

(in Volts, rounded off to two decimal places) is ______ .
Diagram for Electronics and Communication Engineering question 22

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Question 30

Open question
ECMSQ1 markNeeds review
Which of the following statements is/are TRUE with respect to ideal MOSFET-based DC-coupled single-stage amplifiers having finite load resistors?
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Question 43

Open question
ECMCQ2 marksNeeds review
The identical MOSFETs M₁ and M₂ in the circuit given below are ideal and biased in the saturation region. M₁ and M₂ have a transconductance

of 5 mS.
The input signals (in Volts) are:


The output signal

(in Volts) is ________.
Diagram for Electronics and Communication Engineering question 43

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Question 47

Open question
ECMCQ2 marksNeeds review
In the circuit shown, the identical transistors Q1 and Q2 are biased in the active region with β = 120. The Zener diode is in the breakdown region with VZ = 5 V and IZ = 25 mA.
If IL = 12 mA and VEB1 = VEB2 = 0.7 V, then the values of R1 and R2 (in kΩ, rounded off to one decimal place) are ______, respectively.
Diagram for Electronics and Communication Engineering question 47

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Question 17

Open question
ECMCQ1 markNeeds review
In the circuit below, assume that the long channel NMOS transistor is biased in saturation. The small signal trans-conductance for the transistor is

. Neglect body effect, channel length modulation and intrinsic device capacitances. The small signal input impedance

is ______.
Diagram for Electronics and Communication Engineering question 17

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Question 18

Open question
ECMCQ1 markNeeds review
For the closed loop amplifier circuit shown below, the magnitude of open loop low frequency small signal voltage gain is 40.
Diagram for Electronics and Communication Engineering question 18

All the transistors are biased in saturation. The current source

is ideal. Neglect body effect, channel length modulation and intrinsic device capacitances. The closed loop low frequency small signal voltage gain

(rounded off to three decimal places) is ____.
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