# Electronics and Communication Engg - GATE 2013 Paper Solution

Question No. 1

A bulb in a staircase has two switches, one switch being at the ground floor and the other one at the first floor. The bulb can be turned ON and also can be turned OFF by any one of the switches irrespective of the state of the other switch. The logic of switching of the bulb resembles

Question No. 2

Consider a vector field $\stackrel{\to }{A}\left(\stackrel{\to }{r}\right)$ . The closed loop line integral $\int \stackrel{\to }{A}·\stackrel{\to }{dl}$ can be expressed as

Question No. 3

Two systems with impulse responses h1(t) and h2(t) are connected in cascade. Then the overall impulse response of the cascaded system is given by

Question No. 4

In a forward biased pn junction diode, the sequence of events that best describes the mechanism of current flow is

Question No. 5

In IC technology, dry oxidation (using dry oxygen) as compared to wet oxidation (using steam or water vapor) produces

Question No. 6

The maximum value of $\theta$ until which the approximation $\mathrm{sin}\theta \approx \theta$ holds to within 10% error is

Question No. 7

The divergence of the vector field $\stackrel{\to }{A}=x{\stackrel{^}{a}}_{x}+y{\stackrel{^}{a}}_{y}+z{\stackrel{^}{a}}_{z}$ is

Question No. 8

The impulse response of a system is $h\left(t\right)=tu\left(t\right)$.For an input $u\left(t-1\right)$ , the output is

Question No. 9

The Bode plot of a transfer function G(s) is shown in the figure below.

The gain is 32 dB and -8 dB at 1 rad/s and 10 rad/s respectively. The phase is negative for all ω. Then G(s) is

Question No. 10

In the circuit shown below what is the output voltage (Vout) if a silicon transistor Q and an ideal op-amp are used?

Question No. 11

Consider a delta connection of resistors and its equivalent star connection as shown below. If all elements of the delta connection are scaled by a factor k, k> 0, the elements of the corresponding star equivalent will be scaled by a factor of

Question No. 12

For 8085 microprocessor, the following program is executed.
MVI A, 05H;
MVI B, 05H;
DCR B;
JNZ PTR;
HLT;

At the end of program, accumulator contains

Question No. 13

The bit rate of a digital communication system is R kbits/s. The modulation used is 32-QAM. The minimum bandwidth required for ISI free transmission is

Question No. 14

For a periodic signal $v\left(t\right)=30\mathrm{sin}100t+10\mathrm{cos}300t+6\mathrm{sin}\left(500t+\mathrm{\pi }/4\right)$, the fundamental frequency in rad/s is

Question No. 15

In a voltage-voltage feedback as shown below, which one of the following statements is TRUE if the gain k is increased?

Question No. 16

A band-limited signal with a maximum frequency of 5 kHz is to be sampled. According to the sampling theorem, the sampling frequency which is not valid is

Question No. 17

In a MOSFET operating in the saturation region, the channel length modulation effect causes

Question No. 18

Which one of the following statements is NOT TRUE for a continuous time causal and stable LTI system?

The minimum eigenvalue of the following matrix is $\left[\begin{array}{ccc}3& 5& 2\\ 5& 12& 7\\ 2& 7& 5\end{array}\right]$
A polynomial $f\left(x\right)={a}_{4}{x}^{4}+{a}_{3}{x}^{3}+{a}_{2}{x}^{2}+{a}_{1}x-{a}_{0}$ with all coefficients positive has