Courses

# Electronics And Communication - ECE 2014 GATE Paper (Practice Test)

## 65 Questions MCQ Test GATE Past Year Papers for Practice (All Branches) | Electronics And Communication - ECE 2014 GATE Paper (Practice Test)

Description
This mock test of Electronics And Communication - ECE 2014 GATE Paper (Practice Test) for GATE helps you for every GATE entrance exam. This contains 65 Multiple Choice Questions for GATE Electronics And Communication - ECE 2014 GATE Paper (Practice Test) (mcq) to study with solutions a complete question bank. The solved questions answers in this Electronics And Communication - ECE 2014 GATE Paper (Practice Test) quiz give you a good mix of easy questions and tough questions. GATE students definitely take this Electronics And Communication - ECE 2014 GATE Paper (Practice Test) exercise for a better result in the exam. You can find other Electronics And Communication - ECE 2014 GATE Paper (Practice Test) extra questions, long questions & short questions for GATE on EduRev as well by searching above.
QUESTION: 1

Solution:
QUESTION: 2

Solution:
QUESTION: 3

### 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.

Solution:
QUESTION: 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→0.167; 2→0.167; 3→0.152; 4→
0.166; 5→0.168; 6 →0.180. We call this die

Solution:

For a very large number of throws, the frequency should be same for unbiased throw. As it not same, then the die is baised.

*Answer can only contain numeric values
QUESTION: 5

Fill in the missing number in the series.
2   3   6   15   ___   15 7.5    630

Solution:

2nd number/ Ist number
is in increasing order as shown above

QUESTION: 6

Q. No. 6 – 10 Carry One Mark Each

Q.

Find the odd one in the following group
Q,W,Z,B           B,H,K,M           W,C,G,J                  M,S,V,X

Solution:

QUESTION: 7

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?

Solution:
*Answer can only contain numeric values
QUESTION: 8

sum of eight consecutive odd numbers is 656. The average of four consecutive even
numbers is 87. What is the sum of the smallest odd number and second largest even number?

Solution:

Eight consecutive odd number =656
a-6, a-1, a-2, a ,a+2 ,a+4, a+6
a+8=656
a=81
Smallest m=75 … (1)
Average consecutive even numbers

(a-2+a+a+2+a+4)/4=87

a=86

Second largest number =88
1+2=163

QUESTION: 9

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?

Solution:

QUESTION: 10

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?

Solution:

Vhalf= 30(s) drawing rate = s
Total volume =60 S tank
(s1 )(10)- (s)10= 30s
s1 (s) -s= 3s
s1= 4s
s1= 4drawing rate

*Answer can only contain numeric values
QUESTION: 11

Q. No. 11 – 35 Carry One Mark Each

Q.

The determinant of matrix A is 5 and the determinant of matrix B is 40. The determinant of
matrix AB is ________.

Solution:

*Answer can only contain numeric values
QUESTION: 12

Let X be a random variable which is uniformly chosen from the set of positive odd numbers
less than 100. The expectation E[X]is __________.

Solution:

QUESTION: 13

For 0 t < ∞, the maximum value of the function f(t) =e-t -  2e-2t  occurs at

Solution:

QUESTION: 14

The value of

Solution:

QUESTION: 15

If the characteristic equation of the differential equation

has two equal roots, then the values of α are

Solution:

For equal roots, Discriminant B2 − 4AC = 0
4α-4 =0

α = 1

QUESTION: 16

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

Solution:

Norton’s theorem

*Answer can only contain numeric values
QUESTION: 17

In the figure shown, the ideal switch has been open for a long time. If it is closed at t=0, then
the magnitude of the current (in mA) through the 4k? resistor at t = 0+ is _______.

Solution:

QUESTION: 18

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 cm-3. Assuming complete
impurity ionization, the equilibrium electron and hole concentrations are

Solution:

QUESTION: 19

An increase in the base recombination of a BJT will increase

Solution:
QUESTION: 20

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

Solution:
QUESTION: 21

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

Solution:

By opening the output feed back signed becomes zero. Hence it is current sampling.
As the feedback signal  vf is subtracted from the signal same vs it is series mixing

QUESTION: 22

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

Solution:

*Answer can only contain numeric values
QUESTION: 23

A cascade connection of two voltage amplifiers A1 and A2 is shown in the figure. The openloop
gain Av0, input resistance Rin, and output resistance RO for A1 and A2 are as follows:

Solution:

QUESTION: 24

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

Solution:

For an n-variable Boolean function, the maximum number of prime implicants
=2(n -1)

*Answer can only contain numeric values
QUESTION: 25

The number of bytes required to represent the decimal number 1856357 in packed BCD
(Binary Coded Decimal) form is __________ .

Solution:

In packed BCD (Binary Coded Decimal) typically encoded two decimal digits within a single
byte by taking advantage of the fact that four bits are enough to represent the range 0 to 9.
So, 1856357 is required 4-bytes to stored these BCD digits

QUESTION: 26

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

Solution:

QUESTION: 27

An FIR system is described by the system function

Solution:

Minimum phase system has all zeros inside unit circle maximum phase system has all zeros outside unit circle mixed phase system has some zero outside unit circle and some zeros inside unit circle.

One zero is inside and one zero outside unit circle hence mixed phase system

QUESTION: 28

Let x[n] = x[-n]. Let X(z) be the z-transform of x[n]. If 0.5 + j 0.25 is a zero o X(z), which
one of the following must also be a zero of X(z).

Solution:

Given x[n] = x[−n]
x(z ) =x(z)-1 Time reversal property in z -transform
if one zero is 0.5 +j0.25

then other zero will be 1/(0.5+j0.25)

*Answer can only contain numeric values
QUESTION: 29

Consider the periodic square wave in the figure shown.

The ratio of the power in the 7th harmonic to the power in the 5th harmonic for this waveform
is closest in value to _______.

Solution:

For a periodic sequence wave, nth harmonic component is α(1/n)
 power in nth harmonic component is α(1/n2)
 Ratio of the power in 7th harmonic to power in 5th harmonic for given waveform is

*Answer can only contain numeric values
QUESTION: 30

The natural frequency of an undamped second-order system is 40 rad/s. If the system is
damped with a damping ratio 0.3, the damped natural frequency in rad/s is ________.

Solution:

QUESTION: 31

For the following sytem

When X1( s) = 0 , the transfer function

Solution:

QUESTION: 32

The capacity of a band-limited additive white Gaussian noise (AWGN) channel is given by  bits per second (bps), where W is the channel bandwidth, P is the
average power received and σis the one-sided power spectral density of the AWGN. For a
fixed P/σ2 =1000. the channel capacity (in kbps) with infinite bandwidth (W→∞) is
approximately

Solution:

*Answer can only contain numeric values
QUESTION: 33

Consider sinusoidal modulation in an AM system. Assuming no overmodulation, the
modulation index (μ) when the maximum and minimum values of the envelope,
respectively, are 3 V and 1 V, is ________.

Solution:

*Answer can only contain numeric values
QUESTION: 34

To maximize power transfer, a lossless transmission line is to be matched to a resistive load
impedance via a λ / 4 transformer as shown.

The characteristic impedance (in?) of the λ / 4 transformer is _________.

Solution:

QUESTION: 35

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

Solution:

For TEM wave
Electric field (E), Magnetic field (H) and
Direction of propagation (P) are orthogonal to each other.
Here P = + ax
By verification
E =-2ay , H  =-3az
E x H=- ay x -a = +ax→ P

QUESTION: 36

Q. No. 36 – 65 Carry Two Marks Each

Q.

The system of linear equations

Solution:

*Answer can only contain numeric values
QUESTION: 37

The maximum value of the determinant among all 2×2 real symmetric matrices with trace 14
is ________.

Solution:

Using maxima and minima of a function of two variables, we have f is maximum at
x = 0, y = 7 and therefore, maximum value of the determinant is 49

*Answer can only contain numeric values
QUESTION: 38

Solution:

*Answer can only contain numeric values
QUESTION: 39

A series LCR circuit is operated at a frequency different from its resonant frequency. The operating frequency is such that the current leads the supply voltage. The magnitude of current is half the value at resonance. If the values of L, C and R are 1 H, 1 F and 1?? ,
respectively, the operating angular frequency (in rad/s) is ________.

Imp : you should answer only the numneric value

Solution:

The operating frequency (wx), at which current leads the supply.
i.e., wx < wr
again magnitude of current is half the value at resonance

*Answer can only contain numeric values
QUESTION: 40

In the h-parameter model of the 2-port network given in the figure shown, the value of h22 (in
S) is _____ .

Imp : you should answer only the numneric value

Solution:

If two, π−n ws are connected in parallel,

QUESTION: 41

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?

Solution:

*Answer can only contain numeric values
QUESTION: 42

In the magnetically coupled circuit shown in the figure, 56 % of the total flux emanating from one coil links the other coil. The value of the mutual inductance (in H) is ______ .

Solution:
*Answer can only contain numeric values
QUESTION: 43

Assume electronic charge q = 1.6×10-19 C, kT/q = 25 mV and electron mobility  μn = 1000 cm2/V-s. If the concentration gradient of electrons injected into a P-type silicon sample is 1×1021/cm4, the magnitude of electron diffusion current density (in A/cm2) is _________.

Solution:

*Answer can only contain numeric values
QUESTION: 44

Consider an abrupt PN junction (at T = 300 K) shown in the figure. The depletion region
width Xn on the N-side of the junction is 0.2 μm and the permittivity of silicon ( εsi )  is
1.044×10-12 F/cm. At the junction, the approximate value of the peak electric field (in kV/cm)
is _________.

Imp : you should answer only the numneric value

Solution:

QUESTION: 45

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

Solution:

QUESTION: 46

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

Solution:

QUESTION: 47

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

Solution:

*Answer can only contain numeric values
QUESTION: 48

For the MOSFETs shown in the figure, the threshold voltage |Vt| = 2V and

. The value of ID (in mA) is ________.

Solution:

QUESTION: 49

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

Solution:

This circuit has used negative edge triggered, so output of the D-flip flop will changed only
when CLK signal is going from HIGH to LOW (1 to 0)

This is a synchronous circuit, so both the flip flops will trigger at the same time and will
respond on falling edge of the Clock. So, the correct output (Y) waveform is associated to w3 waveform.

QUESTION: 50

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

Solution:

QUESTION: 51

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

Solution:

This circuit diagram indicating that it is memory mapped I/O because to enable the 3-to-8
decoder  is required active low signal through  is required active low through it means I/o device read the status of device LDA instruction is
Again to enable the decoder o/p of AND gate must be 1 and  Ds2 signal required is 1 which is the o/p of multi-i/p AND gate to enable I/O device.
So,

*Answer can only contain numeric values
QUESTION: 52

Consider a discrete-time signal

If y[n] is the convolution of x[n] with itself, the value of y[4] is _________.

Solution:

QUESTION: 53

The input-output relationship of a causal stable LTI system is given as

y[n] = αy[n −1] + βx[n]

If the impulse response h[n] of this system satisfies the condition relationship between α and β is

Solution:

*Answer can only contain numeric values
QUESTION: 54

The value of the integral  is ______________________

Imp : you should answer only the numneric value

Solution:

QUESTION: 55

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

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

Solution:

Solution of state equation of

X(t) =L-1[SI-A-1].X(0)

*Answer can only contain numeric values
QUESTION: 56

The Bode asymptotic magnitude plot of a minimum phase system is shown in the figure

If the system is connected in a unity negative feedback configuration, the steady state error of
the closed loop system, to a unit ramp input, is_________.

Solution:

→ Due to initial slope , it is a type-1 system, and it has non zero velocity error coefficient
( Kv)
→ The magnitude plot is giving 0dB at 2 r / sec.
Which gives kv

QUESTION: 57

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

The corresponding system is

Solution:

*Answer can only contain numeric values
QUESTION: 58

The input to a 1-bit quantizer is a random variable X with pdf  f(x) = 2e−2x for x0 and
fx(x) = 0 for x < 0 , for x < 0 For outputs to be of equal probability, the quantizer threshold
should be _____.

Solution:

One bit quantizer will give two levels.
Both levels have probability of
1/2
Pd of input X is

QUESTION: 59

Coherent orthogonal binary FSK modulation is used to transmit two equiprobable symbol  waveforms

where α = 4mV. Assume an AWGN channel with two-sided noise power spectral density  N0/2=0.5 x 10-12 W/Hz. Using an optimal receiver and the relation  du the bit error probability for a data
rate of 500 kbps is

Solution:

*Answer can only contain numeric values
QUESTION: 60

The power spectral density of a real stationary random process .X(t) is given by

Solution:

*Answer can only contain numeric values
QUESTION: 61

In the figure, M(f) is the Fourier transform of the message signal .m(t) where A = 100 Hz and
B = 40 Hz. Given v(t) = cos (2πfct) and w(t ) = cos( 2π (fc + A) t) , where fc > A The cutoff
frequencies of both the filters are Fc

The bandwidth of the signal at the output of the modulator (in Hz) is _____.

Imp : you should answer only the numneric value

Solution:

QUESTION: 62

If the electric field of a plane wave is

the polarization state of the plane wave is

Solution:

*Answer can only contain numeric values
QUESTION: 63

In the transmission line shown, the impedance Zin (in ohms) between node A and the ground
is _________.

Imp : you should answer only the numneric value

Solution:

*Answer can only contain numeric values
QUESTION: 64

For a rectangular waveguide of internal dimensions a × b(a > b) , the cut-off frequency for
the TE11 mode is the arithmetic mean of the cut-off frequencies for TE10 mode and TE20
mode. If a = √5 cm, the value of b (in cm) is _____.

Solution:

QUESTION: 65

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

Solution:

Integrating, we get V= e-y sin x