2014| SET 2 - (ECE GATE Exam) - Previous Question Paper Solution

Description: GATE Exam Previous Year Question Paper Solution Electronics and Communication (ECE) - 2014 (SET 2)
Number of Questions: 39
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Tags: Electronics and Communication Engineering - EC Analog Circuits Communications Differential Calculus Electronic Devices Matrices and Determinants Vector Calculus
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Choose the most appropriate word from the options given below to complete the following sentence.

Communication and interpersonal skills are ________ important in their own ways.

  1. Each

  2. Both

  3. All

  4. Either


Correct Option: B
Explanation:

Correct option is (2).

Which of the options given below best completes the following sentence?

She will feel much better if she _________

  1. Will get some rest

  2. Gets some rest

  3. Will be getting some rest

  4. Is getting some rest


Correct Option: B
Explanation:

Correct option is (2).

Find the odd one in the following group.

Q, W, Z, B B, H, K, M W, C, G, J M, S, V, X

  1. Q, W, Z, B

  2. B, H, K, M

  3. W, C, G, J

  4. M, S, V, X


Correct Option: C
Explanation:

Correct option is (3).

Lights of four colors (red, blue, green, yellow) are hung on a ladder. On every step of the ladder there are two lights. If one of the lights is red, the other light on that step will always be blue. If one of the lights on a step is green, the other light on that step will always be yellow. Which of the following statements is not necessarily correct?

  1. The number of red lights is equal to the number of blue lights.

  2. The number of green lights is equal to the number of yellow lights.

  3. The sum of red and green lights is equal to sum of the yellow and blue lights.

  4. The sum of red and blue lights is equal to the sum of green and yellow lights.


Correct Option: D
Explanation:

Option (4) is correct.

It takes 30 minutes to empty a half-full tank by draining it at a constant rate. It is decided to simultaneously pump water into the half-full tank while draining it. What is the rate at which water has to be pumped in so that it gets fully filled in 10 minutes?

  1. 4 times the draining rate

  2. 3 times the draining rate

  3. 2.5 times the draining rate

  4. 2 times the draining rate


Correct Option: A
Explanation:

Correct option is (1).

The total exports and revenues from the exports of a country are given in the two charts shown below. The pie chart for exports shows the quantity of each item exported as a percentage of the total quantity of exports. The pie chart for the revenues shows the percentage of the total revenue generated through export of each item. The total quantity of exports of all the items is 500 thousand tonnes and the total revenues are 250 crore rupees. Which item among the following has generated the maximum revenue per kg?

  1. Item 2

  2. Item 3

  3. Item 6

  4. Item 5


Correct Option: D
Explanation:

Correct option is (4).

A regular die has six sides with numbers 1 to 6 marked on its sides. If a very large number of throws show the following frequencies of occurrence:

1 $\rightarrow$ 0.167 2 $\rightarrow$ 0.167 3 $\rightarrow$ 0.152 4 $\rightarrow$ 0.166 5 $\rightarrow$ 0.168 6 $\rightarrow$ 0.180

We call this die

  1. irregular

  2. biased

  3. gaussian

  4. insufficient


Correct Option: B
Explanation:

Correct option is (2).

The value of $\lim\limits_{x \rightarrow \infty}$$\bigg(1 + \frac{1}{x}\bigg)^2$

  1. ln 2

  2. 1.0

  3. e

  4. $\infty$


Correct Option: C
Explanation:

Norton's theorem states that a complex network connected to a load can be replaced with an equivalent impedance

  1. in series with a current source

  2. in parallel with a voltage source

  3. in series with a voltage source

  4. in parallel with a current source


Correct Option: D
Explanation:

Choose the most appropriate pair of words from the options given below to complete the following sentence.

She could not _________ the thought of _________ the election to her bitter rival.

  1. Bear, loosing

  2. Bare, loosing

  3. Bear, losing

  4. Bare, losing


Correct Option: C
Explanation:

Correct option is (3).

For 0 $\leq$ t < $\infty$, the maximum value of the function f(t) = e–t – 2e–2t occurs at

  1. t = loge 4

  2. t = loge 2

  3. t = 0

  4. t = loge 8


Correct Option: A
Explanation:

In CMOS technology, shallow P-well or N-well regions can be formed using

  1. low pressure chemical vapour deposition

  2. low energy sputtering

  3. low temperature dry oxidation

  4. low energy ion-implantation


Correct Option: D
Explanation:

Correct option is (4).

The feedback topology in the amplifier circuit (the base bias circuit is not shown for simplicity) in the figure is

  1. Voltage shunt feedback

  2. Current series feedback

  3. Current shunt feedback

  4. Voltage series feedback


Correct Option: B
Explanation:

An increase in the base recombination of a BJT will increase

  1. the common emitter dc current gain b

  2. the breakdown voltage BVCEO

  3. the unity-gain cut-off frequency fT

  4. none of these


Correct Option: B
Explanation:

Correct option is (2).

In the differential amplifier shown in the figure, the magnitudes of the common mode and differential-mode gains are ACM and Ad, respectively. If the resistance RE is increased, then

  1. ACM increases

  2. common-mode rejection ratio increases

  3. Ad increases

  4. common-mode rejection ratio decreases


Correct Option: B
Explanation:

Correct option is (2).

For an n-variable Boolean function, the maximum number of prime implicants is

  1. 2(n – 1)

  2. n/2

  3. 2n

  4. 2(n–1)


Correct Option: D
Explanation:

In a half-subtractor circuit with X and Y as inputs, the Borrow (M) and Difference (N = X – Y) are given by

  1. M = X $\oplus$ Y, N = XY

  2. M = XY, N = X $\oplus$ Y

  3. M = $\bar{X}$ Y, N = X $\oplus$ Y

  4. M = X$\bar{Y}$, N = $\overline{X \oplus Y}$


Correct Option: C
Explanation:

Let x[n] = x[-n]. Let X(z) be the z-transform of x[n]. If 0.5 + j0.25 is a zero of X(z), which one of the following must also be a zero of X(z)?

  1. 0.5 - j0.25

  2. 1/(0.5 + j0.25)

  3. 1/(0.5 - j0.25)

  4. 2 + j4


Correct Option: B
Explanation:

An FIR system is described by the system function

H(z) = 1 + $\frac{7}{2}$ z–1 + $\frac{3}{2}$ z–2

The system is

  1. maximum phase

  2. minimum phase

  3. mixed phase

  4. zero phase


Correct Option: C
Explanation:

A silicon bar is doped with donor impurities ND 2.25 x 1015 atoms/cm3. Given the intrinsic carrier concentration of silicon at T = 300 K is ni = 1.5 x 1010 cm3. Assuming complete impurity ionization, the equilibrium election and hole concentrations are

  1. n0 = 1.5 x 106 cm–3, p0 = 1.5 x 105 cm-3

  2. n0 = 1.5 x 1010 cm–3, p0 = 1.5 x 1015 cm-3

  3. n0 = 2.25 x 1015 cm–3, p0 = 1.5 x 1010 cm-3

  4. n0 = 2.25 x 1015 cm–3, p0 = 1 x 105 cm-3


Correct Option: D
Explanation:

For the following system,

when X1(s) = 0, the transfer function $\frac{Y(s)}{X_2(s)}$ s

  1. $\frac{s + 1}{s^2}$

  2. $\frac{1}{s + 1}$

  3. $\frac{s + 2}{s(s + 1)}$

  4. $\frac{s + 1}{s(s + 2)}$


Correct Option: D
Explanation:

Which one of the following field patterns represents a TEM wave travelling in the positive x direction?

  1. E = + 8$\hat{y}$, H = - 4$\hat{z}$

  2. E = - 2$\hat{y}$, H = - 3$\hat{z}$

  3. E = + 2$\hat{z}$, H = + 2$\hat{y}$

  4. E = - 3$\hat{y}$, H = + 4$\hat{z}$


Correct Option: B
Explanation:

The capacity of a band-limited additive white Gaussian noise (AWGN) channel is given by C = Wlog2 $\bigg( 1 + \frac{P}{\sigma^2 W} \bigg)$ bits per second (bps), where W is the channel bandwidth, P is the average power received and $\sigma$2 is the one sided power spectral density of the AWGN. For a fixed $\frac{P}{\sigma^2}$ = 1000 the channel capacity (in kbps) with infinite bandwidth (W $\rightarrow$ 3) is approximately

  1. 1.44

  2. 1.08

  3. 0.72

  4. 0.36


Correct Option: A
Explanation:

The outputs of the two flip-flops Q1, Q2 in the figure shown are initialized to 0, 0. The sequence generated at Q1 upon application of clock signal is

  1. 01110....

  2. 01010....

  3. 00110....

  4. 01100....


Correct Option: D
Explanation:

For the n-channel MOS transistor shown in the figure, the threshold voltage VTH is 0.8 V. Neglect channel length modulation effects. When the drain voltage VD = 1.6 V, the drain current ID was found to be 0.5 mA. If VD is adjusted to be 2 V by changing the values of R and VDD, the new value of ID (in mA) is

  1. 0.625

  2. 0.75

  3. 1.125

  4. 1.5


Correct Option: C
Explanation:

In the circuit shown, choose the correct timing diagram of the output (y) from the given waveforms W1, W2, W3 and W4.

  1. W1

  2. W2

  3. W3

  4. W4


Correct Option: C
Explanation:

For the 8085 microprocessor, the interfacing circuit to input 8-bit digital data (DI0- DI7) from an external device is shown in the figure. The instruction for correct data transfer is

  1. MVI A, F8H

  2. IN F8H

  3. OUT F8H

  4. LDA F8F8H


Correct Option: D
Explanation:

Correct option is (4). LDA F8F8H is the correct answer as it shifts the data to the accumulator for a 16-bit address.

The diode in the circuit shown has Von = 0.7 Volts but is ideal otherwise. If Vi = 5 sin (wt) Volts, the minimum and maximum values of Vo (in Volts) are, respectively,

    • 5 and 2.7
  1. 2.7 and 5

    • 5 and 3.85
  2. 1.3 and 5


Correct Option: C
Explanation:

Given the diode circuit,

In the figure shown, the capacitor is initially uncharged. Which one of the following expressions describes the current I (t) (in mA) for t > 0?

  1. I (t) = $\frac{5}{3}$ (1 – e–t/r), T = $\frac{2}{3}$ m sec

  2. I (t) = $\frac{5}{2}$ (1 – e–t/r), T = $\frac{2}{3}$ m sec

  3. I (t) = $\frac{5}{3}$ (1 – e–t/r), T = 3 m sec

  4. I (t) = $\frac{5}{2}$ (1 – e–t/r), T = 3 m sec


Correct Option: A
Explanation:

The system of linear equations

$\begin{bmatrix} \ 2 & 1 & 3 \ \ 3 & 0 & 1 \ \ 1 & 2 & 5 \ \end{bmatrix}$$\begin{bmatrix} \ a \ \ b \ \ c \ \end{bmatrix}$$\begin{bmatrix} \ 5 \ \ -4 \ \ 14 \ \end{bmatrix}$

  1. a unique solution

  2. infinitely many solutions

  3. no solution

  4. exactly two solutions


Correct Option: B
Explanation:

The real part of an analytic function f (z) where z = x + jy is given by e–y cos (x). The imaginary part of f (z) is

  1. ey cos (x)

  2. e–y sin (x)

  3. – ey sin(x)

  4. – e–y sin (x)


Correct Option: B
Explanation:

An unforced linear time invariant (LTI) system is represented by

$\begin{bmatrix} \ . \ \ X_1 \ \ . \ X_2 \ \end{bmatrix}$= $\begin{bmatrix} \ -1 & 0 \ \ 0 & -2 \ \end{bmatrix}$$\begin{bmatrix} \ X_1 \ \ X_2 \ \end{bmatrix}$

If the initial condition are x1 (0) = 1 and x2 (0) = – 1, the solution of the state equation is

  1. x1 (t) = - 1, x2 (t) = 2

  2. x1 (t) = – e-t, x2 (t) = 2 e-t

  3. x1 (t) = - e-t, x2 (t) = – e-2t

  4. x1 (t) = - e-t, x2 (t) = – 2 e-t


Correct Option: C
Explanation:

Consider the state space system expressed by the signal flow diagram shown in the figure.

The corresponding system is

  1. always controllable

  2. always observable

  3. always stable

  4. always unstable


Correct Option: A
Explanation:

If the electric field of a plane wave is $\overrightarrow{E}$ (z, t) = x3 cos (wt - kz + 30o) – y4 sin (wt - kz + 45o) (mV/m), the polarization state of the plane wave is

  1. left elliptical

  2. left circular

  3. right elliptical

  4. right circular


Correct Option: A
Explanation:

Correct option is (1).

The input-output relationship of a causal stable LTI system is given as Y[n] = $\alpha$y[n – 1] + $\beta$x[n]

If the impulse response h6n@ of this system satisfies the condition $\sum_{n=0}^\infty h$[n] = 2, the relationship between a and b is

  1. a = 1 - $\beta$/2

  2. a = 1 + $\beta$/2

  3. a = 2$\beta$

  4. a = - 2$\beta$


Correct Option: A
Explanation:

When a silicon diode having a doping concentration of NA = 9 x 10 cm16 on p-side and ND = 1 x 1016 cm-3 on n-side is reverse biased, the total depletion width is found to be 3 $\mu$m. Given that the permittivity of silicon is 1.04 x 10-12 F/cm, the depletion width on the p-side and the maximum electric field in the depletion region, respectively, are

  1. 2.7 $\mu$m and 2.3 x 105 V/cm

  2. 0.3 $\mu$m and 4.15 x 105 V/cm

  3. 0.3 $\mu$m and 0.42 x 105 V/cm

  4. 2.1 $\mu$m and 0.42 x 105 V/cm


Correct Option: B
Explanation:

Coherent orthogonal binary FSK modulation is used to transmit two equiprobable symbol waveforms s1 (t) = acos 2$\pi$f1 t and s2 (t) = $\alpha$cos 2$\pi$f2 t, where $\alpha$ = 4 mV. Assume an AWGN channel with two sided noise power spectral density $\frac{N_0}{2}$ = 0.5 x 10 W/Hz. Using an optimal receiver and the relation Q (v) = $\frac{1}{\sqrt{2 \pi}} \int\limits_v^\infty$$e^{-u^2/2}$ du, the bit error probability for a data rate of 500 kbps is

  1. Q (2)

  2. Q (2 $\sqrt{2}$)

  3. Q (4)

  4. Q (4 $\sqrt{2}$)


Correct Option: C
Explanation:

If the characteristic equation of the differential equation $\frac{d^2 y}{dx^2} + 2 \alpha \frac{dy}{dx} + y = 0$ has two equal roots, then the values of a are

  1. $\pm$ 1

  2. 0, 0

  3. $\pm$ j

  4. $\pm$ 1/2


Correct Option: A
Explanation:

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