Electronics & Communication Gate Yearwise
Electronics and Communication Gate 2018 Questions with Answer
Ques 1 GATE 2018
Consider the following amplitude modulated signal: s(t)=cos(2000πt)+4cos(2400πt)+cos(2800πt). The ratio (accurate to three decimal places) of the power of the message signal to the power of the carrier signal is
Ques 2 GATE 2018
Let c(t)=Accos(2πfct) and m(t)=cos(2πfmt) It is given that fc>>5fm. The signal c(t)+m(t) is applied to the input of a non-linear device, whose output vo(t) is related to the input vi(t) as vo(t)=avi(t)+bvi2(t), where a and b are positive constants. The output of the non-linear device is passed through an ideal band-pass filter with center frequency fc and bandwidth 3fm, to produce an amplitude modulated (AM) wave. If it is desired to have the sideband power of the AM wave to be half of the carrier power, then a/b is
Ques 3 GATE 2018
Let the input be u and the output be y of a system, and the other parameters are real constants. Identify which among the following systems is not a linear system:
Ques 4 GATE 2018
The Nyquist stability criterion and the Routh criterion both are powerful analysis tools for determining the stability of feedback controllers. Identify which of the following statements is FALSE:
Ques 5 GATE 2018
The state equation and the output equation of a control system are given below:

Ques 6 GATE 2018
For a unity feedback control system with the forward path transfer function G(s)=K/s(s+2). The peak resonant magnitude Mr of the closed-loop frequency response is 2. The corresponding value of the gain K (correct to two decimal places) is
Ques 7 GATE 2018
The figure below shows the Bode magnitude and phase plots of a stable transfer function G(s)=n0/(s3+d2s2+d1s+d0). Consider the negative unity feedback configuration with gain k in the feedforward path.

Ques 8 GATE 2018
The logic function f(X,Y) realized by the given circuit is

Ques 9 GATE 2018
A function F(A,B,C) defined by three Boolean variables A, B and C when expressed as sum of products is given by F=Ā·B̄·C̄+Ā·B·C̄+A·B̄·C̄ where, Ā, B̄, and C̄ are the complements of the respective variables. The product of sums (POS) form of the function F is
Ques 10 GATE 2018
A traffic signal cycles from GREEN to YELLOW, YELLOW to RED and RED to GREEN. In each cycle, GREEN is turned on for 70 seconds, YELLOW is turned on for 5 seconds and the RED is turned on for 75 seconds. This traffic light has to be implemented using a finite state machine (FSM). The only input to this FSM is a clock of 5 second period. The minimum number of flip-flops required to implement this FSM is
Ques 11 GATE 2018
A four-variable Boolean function is realized using 4×1 multiplexers as shown in the figure. The minimized expression for F(U,V,W,X) is

Ques 12 GATE 2018
A 2x2 ROM array is built with the help of diodes as shown in the circuit below. Here WO and W1 are signals that select the word lines and BO and B1 are signals that are output of the sense amps based on the stored data corresponding to the bit lines during the read operation.

Ques 13 GATE 2018
In the circuit shown below, a positive edge-triggered D Flip-Flop is used for sampling input data Din using clock CK. The XOR gate outputs 3.3 volts for logic HIGH and 0 volts for logic LOW levels. The data bit and clock periods are equal and the value of ΔT/TCK=0.15, where the parameters ΔT and TCK are shown in the figure. Assume that the Flip-Flop and the XOR gate are ideal.

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