Electronics & Communication Gate Yearwise 

Electronics and Communication Gate 2024 Questions with Answer

Ques 27 GATE 2024

As shown in the circuit, the initial voltage across the capacitor is 10 V, with the switch being open.
The switch is then closed at t=0.
The total energy dissipated in the ideal Zener diode $(V_{Z}=5 V)$ after the switch is closed (in mJ, rounded off to three decimal places) is


(1.25) is the correct answer.

Ques 28 GATE 2024

A full scale sinusoidal signal is applied to a 10-bit ADC.
The fundamental signal component in the ADC output has a normalized power of 1 W, and the total noise and distortion normalized power is 10 μW.
The effective number of bits (rounded to the nearest integer) of the ADC is

A

7

B

8

C

9

D

10


(C) is the correct answer.

Ques 29 GATE 2024

The opamps in the circuit shown are ideal, but have saturation voltages of ±10 V.

Assume that the initial inductor current is 0 A. The input voltage (Vi) is a triangular signal with peak voltages of ±2 V and time period of 8 µs. Which one of the following statements is true?

A

$V_{o1}$ will be a square wave and $V_{o2}$ will be a triangle wave.

B

$V_{o1}$ will be a triangle wave and $V_{o2}$ will be a square wave.

C

$V_{o1}$ will be a sine wave and $V_{o2}$ will be a square wave.

D

$V_{o1}$ will be a triangle wave and $V_{o2}$ will be a sine wave.


(A) is the correct answer.

Ques 30 GATE 2024

In the circuit below, the opamp is ideal.

If the circuit is to show sustained oscillations, the respective values of R1 and the corresponding frequency of oscillation are

A

29R and 1/(2π√6 RC)

B

2R and 1/(2πRC)

C

29R and 1/(2πRC)

D

2R and 1/(2π√6 RC)


(b) is the correct answer.

Circuit Description:
This is a Wien Bridge Oscillator circuit with:
• An ideal op-amp
• Feedback resistor Rf from output to inverting input
• Resistor R from inverting input to ground
• Series RC network (C and R) in the positive feedback path
• Parallel RC network (R and C) to ground

For a Wien Bridge Oscillator to produce sustained oscillations, two conditions must be satisfied:

Condition 1: Frequency of Oscillation
The frequency at which the circuit oscillates is determined by the RC network in the positive feedback path.

At the resonant frequency, the phase shift through the RC network is zero, and this occurs when:
f = 1/(2πRC)

Condition 2: Barkhausen Criterion for Sustained Oscillation
For sustained oscillations, the loop gain must equal 1, and the total phase shift around the loop must be 0° (or 360°).

The gain of the RC feedback network at resonance is 1/3.
Therefore, the amplifier gain must be 3 to compensate.

The non-inverting amplifier gain is:
A = 1 + (Rf/R)

Setting this equal to 3:
1 + (Rf/R) = 3
Rf/R = 2
Rf = 2R

Final Answer:
• Rf = 2R
• Frequency of oscillation f = 1/(2πRC)

Answer: Option (B) - 2R and 1/(2πRC)

Ques 31 GATE 2024

In the circuit shown below, the transistors $M_1$ and $M_2$ are biased in saturation.
Their small signal transconductances are $g_{m1}$ and $g_{m2}$ respectively.
Neglect body effect, channel length modulation and intrinsic device capacitances.

Assuming that capacitor $C_1$ is a short circuit at the signal frequency, the magnitude of small signal voltage gain $|\frac{v_{out}}{v_{in}}|$ is

A

$g_{m2} R_D$

B

$R_D (R_B + \frac{1}{g_{m1}})$

C

$\frac{g_{m2} R_D}{R_B + \frac{1}{g_{m1}}}$

D

$\frac{g_{m1} R_D (\frac{1}{g_{m1}})}{\frac{1}{g_{m1}} + R_s}$


(C) is the correct answer.

Ques 32 GATE 2024

Which of the following statements is/are true for a BJT with respect to its DC current gain (β)?

A

Under high-level injection condition in forward active mode, β will decrease with increase in the magnitude of collector current.

B

Under low-level injection condition in forward active mode, where the current at the emitter-base junction is dominated by recombination-generation process, β will decrease with increase in the magnitude of collector current.

C

β will be lower when the BJT is in saturation region compared to when in active region.

D

A higher value of β will lead to a lower value of the collector-to-emitter breakdown voltage.


(A;B;C) is the correct answer.

Ques 33 GATE 2024

Consider a MOS capacitor made with p-type silicon.
It has an oxide thickness of 100 nm, a fixed positive oxide charge of 10-8 C/cm2 at the oxide-silicon interface, and a metal work function of 4.6 eV.
Assume that the relative permittivity of the oxide is 4 and the absolute permittivity of free space is 8.85 × 10-14 F/cm.
If the flatband voltage is 0 V, the work function of the p-type silicon (in eV, rounded off to two decimal places) is


(4.95) is the correct answer.

Ques 34 GATE 2024

A non-degenerate n-type semiconductor has 5% neutral dopant atoms.
Its Fermi level is located at 0.25 eV below the conduction band (EC) and the donor energy level (ED) has a degeneracy of 2.
Assuming the thermal voltage to be 20 mV, the difference between EC and ED (in eV, rounded off to two decimal places) is


(0.28) is the correct answer.

Ques 35 GATE 2024

An NMOS transistor operating in the linear region has IDS of 5 μA at VDS of 0.1 V.
Keeping VGS constant, the VDS is increased to 1.5 V.
Given that μnCox(W/L) = 50 μA/V2, the transconductance at the new operating point (in μA/V, rounded off to two decimal places) is


(4.58) is the correct answer.

Ques 36 GATE 2024

The photocurrent of a PN junction diode solar cell is 1 mA.
The voltage corresponding to its maximum power point is 0.3 V.
If the thermal voltage is 30 mV, the reverse saturation current of the diode (in nA, rounded off to two decimal places) is


(1.66) is the correct answer.

Ques 37 GATE 2024

For a real number $x>1$,
$\frac{1}{log_{2}x}+\frac{1}{log_{3}x}+\frac{1}{log_{4}x}=1$

A

1

B

2

C

3

D

4


(C) is the correct answer.

Ques 38 GATE 2024

The greatest prime factor of $(3^{199}-3^{196})$ is

A

13

B

17

C

3

D

11


(A) is the correct answer.

Ques 39 GATE 2024

Four identical cylindrical chalk-sticks, each of radius $r=0.5$ cm and length $l=10$ cm, are bound tightly together using a duct tape as shown in the following figure.

The width of the duct tape is equal to the length of the chalk-stick.
The area $(in~cm^{2})$ of the duct tape required to wrap the bundle of chalk-sticks once, is

A

$20(4+\pi)$

B

$20(8+\pi)$

C

$10(8+\pi)$

D

$10(4+\pi)$


(C) is the correct answer.

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