## GATE Electronics & Communication Question Papers-02

No. Question

1

A 1 kHz sinusoidal signal is ideally sampled at 1500 samples/sec and the sampled signal is passed through an, ideal low-pass filter with cut-off frequency 800 Hz.

The output signal has the frequency

Options

A) zero Hz B) 0.75 kHz

C) 0.5 kHz D) 0.25 kHz

Your Answer ( Not Answered )

Correct Answer C

2 The minimum number of 2-to -1 multiplexers required to realize a 4-to 1 multiplexer is

Options

A) 1 B) 2

C) 3 D) 4

Your Answer ( Not Answered )

Correct Answer B

3 Choose the correct one front among the alternatives A, B, C, D after matching an item from Group 1 with the most appropriate item, in Group 2.

Group 1 Group 2

P: Shift register 1:Frequency division

Q: Counter 2: Addressingin memory chips

R: Decoder 3: Serial to parallel data conversion

Options

A) P-3, Q- 2, R-1 B) P-3, Q-1, R-2

C) P-2, Q-1, R-3 D) P-1, Q- 2, R-2

Your Answer ( Not Answered )

Correct Answer B

4 A random variable X with uniform density in the interval 0 to 1 is quantized as follows:

If 0 £ X £ 0.3, x q = 0

If 0.3 £ X £ 1, x q = 0.7

where x q is the quantized value of X.

The root-mean square value of the quantization noise is

Options

A) 0.573 B) 0.198

C) 2.205 D) 0.266

Your Answer ( Not Answered )

Correct Answer A

5 In a full-wave rectifier using two ideal diodes, V dc and V m are the dc and peak values of the voltage respectively across a resistive load. If PIV is the peak inverse voltage of the diode, then the appropriate relationships for this rectifier are

Options

A)

V dc =

V m

p

, PIV = 2V m

B) V dc = 2

V m

p

, PIV = 2V m

C) V dc = 2

V m

p

, PIV = V m D) V dc =

V m

p

, PIV = V m

Your Answer ( Not Answered )

Correct Answer B

6 The Fourier transform of a conjugate symmetric function is always

Options

A) imaginary B) conjugate anti-symmetric

C) real D) conjugate symmetric

Your Answer ( Not Answered )

Correct Answer C

7 It is desired to multiply the numbers 0AH by 0BH and store the result in the accumulator. The numbers are available in registers B and C respectively. A Part of

the 8085 program for this purpose is given below:

MVI A, 00H

Loop;- – – – – – – – –

——————–

——————-

HLT END

The sequence of instruction to the complete the program would be

Options

A) JNZ LOOP, ADD B, DCR C B) ADD S, JNZ LOOP, DCR C

C) DCR C, JNZ LOOP, ADD B D) ADD B, DCR C, JNZ LOOP

Your Answer ( Not Answered )

Correct Answer D

8

A solution of the following differential equation is given by

d 2 y

dx 2

–

dy

dx

+ 6y = 0

Options

A)

y = e 2x + e -3x

B)

y = e 2x + e 3x

C)

y = e -2x + e 3x

D)

y = e -2x + e -3x

Your Answer ( Not Answered )

Correct Answer B

9 Consider the following statements S1 and S2.

S1: The threshold voltage (V T ) of a MOS capacitor decreases with increase in gate oxide thickness

S2: The threshold voltage (V T ) of a MOS capacitor decreases with increase in substrate doping concentration

Which one of the following is correct?

Options

A) S1 is FALSE and S2 is TRUE

B) Both S1 and S2 are TRUE

C) Both S1 and S2 are FALSE

D) S1 is TRUE and S2 is FALSE

Your Answer ( Not Answered )

Correct Answer A

10 Consider an abrupt p-junction. Let V bi be the built-in potential of this junction and V R be the applied reverse bias. If the junction capacitance (C j ) is 1 pF for

V bi + V R = 1V, then for V bi + V R – 4V, C j will be

Options

A) 4 pF B) 2 pF

C) 0.25 pF D) 0.5 pF

Your Answer ( Not Answered )

Correct Answer D

11 The impurity commonly used for realizing the base region of a silicon n-p-n transistor is

Options

A) Gallium B) Indium

C) Boron D) Phosphorus

Your Answer ( Not Answered )

Correct Answer C

12 Despite the presence of negative feedback, control system still have problems of instability because the

Options

A) components used have nonlinearities. B) dynamic equations of the subsystems are not known exactly.

C) mathematical analysis involves approximations. D) system has large negative phase angle at high frequencies.

Your Answer ( Not Answered )

Correct Answer A

13 The drain of an n-channel MOSFET is shorted to the gate so that V GS = V DS . The threshold voltage (V T ) of MOSFET is 1 V. If the drain current (I D ) is 1 mA for V GS = 2V, then for V GS = 3V, I D is

Options

A) 2 mA B) 3 mA

C) 9 mA D) 4 mA

Your Answer ( Not Answered )

Correct Answer D

14 Let x(n) = (

1

2

) n u(n), y(n)=x 2 (n) and Y(e j w ) be the Fourier transform of y(n). Then Y(e j0 ) is

Options

A)

1

4

B) 2

C) 4 D)

4

3

Your Answer ( Not Answered )

Correct Answer A

15 Noise with uniform power spectral density of N 0 W/Hz is passed through a filter H ( w ) = 2 exp(-j w t d ) followed by an ideal low pass filter of bandwidth BHz. The output noise power in Watts is

Options

A) 2N 0 B B) 4N 0 B

C) e N 0 B D) 16 N 0 B

Your Answer ( Not Answered )

Correct Answer B

16 Consider the following statements S1 and S2

S1: At the resonant frequency the impedance of a series R-L-C circuit is zero.

S2: In a parallel G-L-C circuit, increasing the conductance G results in increase in its Q factor.

Which one of the following is correct?

Options

A) S1 is FALSE and S2 is TRUE B) Both S1 and S2 are TRUE

C) S1 is TRUE and S2 is FALSE D) Both S1 and S2 are FALSE

Your Answer ( Not Answered )

Correct Answer D

17 A signal x(n) = sin( w 0 n + f ) is the input to a linear time-invariant system having a frequency response H(e (j w ) . If the output of the system Ax(n – n 0 ), then the most general form of ÐH(ejw) will be

Options

A) – n 0 w 0 + b for any arbitrary real b . B) – n 0 w 0 + 2 p k for any arbitrary integer k.

C) n 0 w 0 + 2 p k for any arbitrary integer k. D) -n 0 w 0 f .

Your Answer ( Not Answered )

Correct Answer B

18 Consider a lossless antenna with a directive gain of +6dB. If 1 mW of power is fed to it the total power radiated by the antenna will be

Options

A) 4 mW B) 1 mW

C)

7 mW D) 1/4 mW

Your Answer ( Not Answered )

Correct Answer A

19 A MOS capacitor made using p type substrate is in the accumulation mode. The dominant charge in the channel is due to the presence of

Options

A) holes B) electrons

C) positively charged ions D) negatively charged ions

Your Answer ( Not Answered )

Correct Answer B

20

Choose the correct one from among the alternatives A, B, C, D after matching an item from Group 1 with the most appropriate item in Group 2.

Group1 Group 2

1 : FM

2 : DM

3 : PSK

4 : PCM P : Slope overload

Q : m -law

R : Envelope detector

S : Capture effect

T : Hilbert transform

U : Matched filter

Options

A) 1-T, 2-P, 3-U, 4-S B) 1-S, 2-U, 3-P, 4-T

C) 1-S, 2-P, 3-U, 4-Q D) 1-U, 2-R, 3-S, 4-Q

Your Answer ( Not Answered )

Correct Answer C

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