Electronics and Communication GATE 2016 Set-1 Questions with Answer

Ques 1 Analog Communication


The block diagram of a frequency synthesizer consisting of a Phase Locked Loop (PLL) and a divide-by-N counter (comprising 2,4,8,16 outputs) is sketched below. The synthesizer is excited with a 5 kHz signal (Input 1). The free-running frequency of the PLL is set to 20 kHz. Assume that the commutator switch makes contacts repeatedly in the order 1-2-3-4. The corresponding frequencies synthesized are:

A

10 kHz, 20 kHz, 40 kHz, 80 kHz

B

20 kHz, 40 kHz, 80 kHz, 160 kHz

C

80 kHz, 40 kHz, 20 kHz, 10 kHz

D

160 kHz, 80 kHz, 40 kHz, 20 kHz


Ques 2 Analog Communication


A superheterodyne receiver operates in the frequency range of 5-68 MHz. The intermediate frequency fIF and local oscillator frequency fLO are chosen such that fIF≤fLO. It is required that the image frequencies fall outside the 5-68 MHz band. The minimum required fIF (in MHz) is

5 is the correct answer.


Ques 3 Analog Communication


The amplitude of a sinusoidal carrier is modulated by a single sinusoid to obtain the amplitude modulated signal s(t)=5cos(1600πt)+20cos(1800πt)+5cos(2000πt). The value of the modulation index is

0.5 is the correct answer.


Ques 4 Control Systems


Match the inferences X, Y, and Z, about a system, to the corresponding properties of the elements of first column in Routh's Table of the system characteristic equation.

A

X-P, Y-R, Z-Q

B

X-Q, Y-P, Z-R

C

X-R, Y-P, Z-Q

D

X-P, Y-Q, Z-R


Ques 5 Control Systems


A closed-loop control system is stable if the Nyquist plot of the corresponding open-loop transfer function

A

encircles the s-plane point (-1+j0) in the counterclockwise direction as many times as the number of right-half s-plane poles.

B

encircles the s-plane point (0-j1) in the clockwise direction as many times as the number of right-half s-plane poles.

C

encircles the s-plane point (-1+j0) in the counterclockwise direction as many times as the number of left-half s-plane poles.

D

encircles the s-plane point (-1+j0) in the counterclockwise direction as many times as the number of right-half s-plane zeros.


Ques 6 Control Systems


The open-loop transfer function of a unity-feedback control system is G(s)=k/(s2+5s+5). The value of K at the breakaway point of the feedback control system's root-locus plot is

2.8 is the correct answer.


Ques 7 Control Systems


The open-loop transfer function of a unity-feedback control system is given by G(s)=K/(s(s+2)). For the peak overshoot of the closed-loop system to a unit step input to be 10%, the value of K is

2.9 is the correct answer.


Ques 8 Control Systems


The transfer function of a linear time invariant system is given by H(s)=2s4-5s3+5s-2. The number of zeros in the right half of the s-plane is

3 is the correct answer.


Ques 9 Digital Circuits


The output of the combinational circuit given below is

A

0 V

B

(|VT| of PMOS + VT of NMOS) / 2

C

Switching threshold of inverter

D

VDD


Ques 10 Digital Circuits


Identify the circuit below.

A

Binary to Gray code converter

B

Binary to XS3 converter

C

Gray to Binary converter

D

XS3 to Binary converter


Ques 11 Digital Circuits


The functionality implemented by the circuit below is

A

2-to-1 multiplexer

B

4-to-1 multiplexer

C

7-to-1 multiplexer

D

6-to-1 multiplexer


Ques 12 Digital Communication


Consider binary data transmission at a rate of 56 kbps using baseband binary pulse amplitude modulation (PAM) that is designed to have a raised-cosine spectrum. The transmission bandwidth (in kHz) required for a roll-off factor of 0.25 is

35 is the correct answer.


Ques 13 Digital Communication


Consider a discrete memoryless source with alphabet S={s0,s1,s2,s3,s4,...} and respective probabilities of occurrence P={1/2,1/4,1/8,1/16,1/32,...}. The entropy of the source (in bits) is

2 is the correct answer.


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