1 An LTI system has the input signal Which of the following sequence of operations is most appropriate to get output -MIL). Interpolation by Delay by Decimation by L Delay by Interpolation by Decimation by M Decimation by Delay by Interpolation by L Interpolation by Decimation by delay by M
2 Consider a low pass random process with a white noise power spectral density Sx(oo) =NI2 where -2nB:5 00:5 2nB
o elsewhere
The Auto-correlation function is
2NBsinc(2nB-r)
nNBsinc(2nB-r)
NBsinc(2nB-r)
none of the above

3 Pole-zero plot of a digital filter is shown below, what is the type of filter? 1m

Re
2
a)Low Pass High Pass Band Stop All Pass
4 Determine the DTFT of the sequence lal 1 . urn] is unit step sequence. Y(ejO) 1 j e-j O)2
Y(ejO) 11 a e-j O)2
I e-jO)2
none of the above

5 The function has the Fourier transform g(oo). The Fourier transform of is 12n 12n 2n none of the above
18 2010 ELECTRONICS AND COMMUNICATION ENGINEERING
SET-A

6 The purpose of Design for Test process in ASIC design flow is
To capture functional errors
To capture manufacturing defects
To capture timing violations
For radiation mitigation

7 The coupling between the two inductors is increased from zero in the circuit shown. Which of the following statements is true?,

R

L

L 120
c
•


The resonant frequency will increase and the Q will decrease The resonant frequency and Q will both increase. The resonant frequency and Q will both decrease The resonant frequency will decrease and the Q will increase

SET-A


18

8 Write a Boolean expression for Z in terms of D and E. You need not simplify the expression.

r-C

. .


False
9 A parallel plate capacitor of 100 pf having an air dielectric is charged to 10 kilovolts. It is then electrically isolated. The plates are pulled away from each other until the distance is ten times more than before. Estimate the energy needed to pull the plates.. 0.05 Joules 50 Joules
.-F"
500 Joules d) -50 Joules
10 How could Schroedinger's equation be relevant in the practical design of a Cathode­Ray Tube? To optimize the colour quality To optimize the picture sharpness It is not relevant, because the CRT contains no crystalline lattice structure Its effects are negligible, as the electron wavelength is very small compared to the spot size


18

11 When compared with stripline, the major disadvantage of microstrip line is Not amenable for printed circuit technique. More expensive and complex to manufacture. Bulkier and voluminous. More likely to radiate.
12 The disadvantage of single-stub matching as compared to double-stub matching, is that The stub position has to be adjustable Only shunt stub can be used Only resistive load can be matched Useful only in two wire transmission line


13 A charge Q2 =8.854 xlO-9 C is located in a vacuum at The force on Q2 due to a charge QI=4n xlO-3 C at PI is ay N -5.4ax+6.3ay-5.4az N 5.4ax-6.3ay-5.4az N None
14 If a material contains 1020 molecules/m3, each molecule having a moment of
8.854 X 10-27 C-m parallel to an electric field of 105 Vim, then its dielectric constant is 2.2 b)2 c)4 12
15 Ifevery minor of order of a matrix'A' is zero, then rank is greater than equal to less than or equal to less than
16 Which of the following is true The product of the eigenvalues of a matrix is equal to the trace of the matrix The eigenvalues of a skew-symmetric matrix are real A is a nonzero column matrix and B is a nonzero row matrix, then rank of AB is
one A system of linear non-homogeneous equations is consistent if and only if the rank of the coefficient matrix is less than or equal to the rank of the augmented matrix
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17 What is the maximum clock frequency at which following circuit can be operated without timing violations? Assume that the Combinational logic delay is 10 ns and the clock duty cycle varies from 40% to 60

o Q
Clock

100 MHz 50 MHz 40 MHz 25 MHz
18 Following shift register is initially loaded with the bit pattern "1010". After how many clock cycles will the content of shift register be "1010" again?
clock

o 1
Serial
input




5 b)9 c)7 d)15
19 Which one of the following is the lowest level of abstraction for representation of a digital system? VHDLNerilog GDS-II Gate level netlist SystemC
20 The content of the accumulator of 8085 microprocessor after execution of the following instructions will be MVI A,A7h
ORA A
RLC
FFh b)4Fh c)3Fh d) CEh



..
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18
2010 ELECTRONICS AND COMMUNICATION ENGINEERING SET-A
21 For CMOS implementation of2 input XOR logic gate, how many nMOS and pMOS transistors are required? 2 nMOS and 2 pMOS 3 nMOS and 3 pMOS 6 nMOS and 6 pMOS 8 nMOS and 8 pMOS
22 Which of the following principles is applied while designing the output matching
network for a high power Class-C amplifier?
Maximum Power Transfer Theorem
Norton's Theorem
Thevenin's Theorem

Power =(voltage)2 RL
23 Find the approximate output impedance of the VCCS (voltage-controlled current source) based circuit at port Yo.
Vin Vee




lees
gm O.OlS Rin =10MQ

Vo
lOOkQ

0.01 n b) 100 n 100 kn 10 Mn
24 Which of the following parameters of a Silicon Schottky Diode is higher than
that of a corresponding PN junction diode?
Forward voltage drop Reverse recovery current
Reverse recovery time Reverse leakage current




18
25 Assume the intrinsic standoff ratio for the UJT is 0.8 for the relaxation oscillator circuit given below. The frequency of oscillation of this circuit is approximately equal to
R3 10k C1 O.1uF R1 100 ohm UJT R2 39 ohms 12Vdc


1.43 kHz 620 Hz 7kHz 1.6kHz 26 The approximate frequency of oscillation of the circuit shown below is

5V
10k
1k
10k
O.01uF
O.01uF


1k
Q3

803kHz 16.6kHz 7.2kHz 3.6kHz
Electronics and Communication Engineering
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27 A unit step voltage travels from left to right along an infinite transmission line. It hits an inductive discontinuity at t=O. What will be the waveform immediately to the left of the discontinuity? Positive spike on a unit step Unit step with reduced rise time Attenuated unit step Magnified unit step
28 A lossy open stub having a length of 1132 wavelength, is approximately equivalent to A small capacitor in shunt with a small resistor A small capacitor in shunt with a large resistor A small inductor in shunt with a small resistor A large inductor in shunt with a large resistor
29 Ampere's law relates
Electric field and Charge Electric field and Current
Magnetic field and Current Magnetic field and Charge

30 Across which type of boundary does the electric field have a continuous tangential component?
Charge free boundary Current free boundary
Any boundary Charged boundary

31 Laplace Transform of eattn is
32 For x 00 Y the partial differential equation 2 a2u 2 a2u •
X ax2 ay2 0 IS
parabolic Hyperbolic
Elliptic Nature connote be predicted

33 A CMOS digital circuit consumes P watts of dynamic power while operating at 20 MHz clock frequency and 5V supply. What will be its dynamic power consumption if the clock frequency is increased to 40 MHz and supply voltage is decreased to 2.5V? P/4 P12 P d)2P


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2010 ELECTRONICS AND COMMUNICATION ENGINEERING SET-A
34 A communication channel with Additive White Gaussian Noise, has a bandwidth of 4 kHz and SNR of 31dB. Its channel capacity is 1.6 kbps b)20 kbps 32 kbps 256 kbps
35 Ifthe total power of an amplitude modulated signal is 600W and the carrier power is 400W, the modulation index is 0.75 0.5 0.25 1
36 What is the advantage of Offset QPSK (OQPSK) compared to conventional QPSK? Constant envelope Bandwidth efficiency Simple demodulator All of above
37 An angle modulated signal with carrier frequency roc 2n x 105 is described by the equation 10 cos (roct 5 sin(3000nt) 10 sin(2000nt) What is the frequency deviation Af?
12387.32 Hz 17500 Hz 20000 Hz 15000 Hz
38 The Fourier transform of a signal =e-4ltl is 8 ro2 _ro2 4 ro2 ro2
39 What is the output waveform Vo for a sinusoidal input of peak-peak amplitude of 4V. Assume that Zl and Z2 are two identical Zener diodes of 4.7V, and Rl=10kohm and
R2=20kohm.
Z1 Z2
R2
vee
R1
Ul au
Vo



Same as input Sinusoidal waveform with 5AV peak Sinusoidal waveform clamped to Sinusoidal waveform clamped to


Electronics and Communication Engineering

I
40 For a particular toroidal inductor core, the inductance value obtained for 50 Turns is 200ItH. Iftwo such inductors are wired in parallel, the resulting inductance is 200ItH 50ItH 400ItH 100ItH
41 The magnetic equivalent of Ohm's Law is
Lenz's Law b) Faraday's Law
Rowland's Law d) Maxwell's Law
42 It is required to design a class B output stage (as shown below) to deliver an average output power of 12.5W to a load of 40. The power supply is selected so that Vcc is 5V greater than the peak output voltage. Determine the power conversion efficiency. of the circuit.
+Vee
2
Vi
2

4 OHM
-Vee

48% 50% 52% d) 54%
Electronics and Communication Engineering SET-A
•



18
43 Which type of circuit has an input impedance as shown in this polar plot?



A resistance, capacitor and inductor in series


A resistance, capacitor and inductor in parallel


A resistance in shunt with a series combination of an inductor and a capacitor


A resistance in series with a shunt combination of an inductor and a capacitor


44 A coaxial transmission line carrying an RF signal is perfectly matched to the load. Consider the cross-section of the line, at a plane where the instantaneous voltage is at its maximum value. How will the curl of the E-field vary over this cross-section? Increases from the center to the outer conductor Decreases from the center to the outer conductor Zero everywhere Constant value proportional to the RF voltage
45 The continuity of the tangential field component at the interface of two media for normal incidence of a plane wave requires
b)T f f d) f
46 Which mode of a circular waveguide will have the lowest attenuation?
TEll Mode TMol Mode TE21 Mode d) TEol Mode
47 If<j> 2x2y_xz3, then the Laplacian of is 4yz-6xz 4z-6xy 4y-6xz 2xy-6yz
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48 What does the following integral evaluate to?


fSin6B.dB
o

51t/16 5 1t/8 0 d) 51t/32
49 A signal with two frequency components at 6 kHz and 12 kHz, is sampled at the rate of 16 kHz and then passed through a Low Pass filter having a cut-off frequency of 16 kHz. The output signal of the filter is an undistorted version of the original signal contains the 6 kHz component and aspurious component of 4 kHz contains only the 6 kHz components contains both the components of the original signal and two spurious components
of4kHzand 6 kHz
50 What is the greatest allowable PRF for unambiguous reception in a radar having a maximum range of 120 km? 1250 pps 2500 pps 1200 pps 5000 pps
51 A microprocessor has a cache memory with access time of 2 ns and a main memory with access time of 10 ns. Ifthe cache miss ratio is 0.6, what is the average memory access time? a)6.8ns b)6ns c)5.2ns d)12ns
52 Consider the following assembly code for a hypothetical RISC processor with a 4-stage pipeline (Instruction Fetch, Decode/Register Read, Execute and Write).
add rl,r2,rJ II r1 r2+r3
sub r4,rl,rJ II r4 rl-rJ
mul r5,r2,rJ IIr5 r2*rJ

Identify the possible pipeline hazard and the affected instruction.
Read after write hazard during mul
Read after write hazard during sub
Read after write hazard during add
Write after write hazard during mul

53 A zero memory source emits six messages with probabilities 0.3,0.25,0.15,0.12,0.1
and 0.08. Ifbinary Huffman coding is used, what will be the average code length?
2.45 bits 3.45 bits 2.54 bits 3.54 bits



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54 In the circuit given below, assume that Vcc= 15V; Zl, Z2, Z3 Z4 are identical zener diodes with breakdown voltage of5V; R1= R4 5kO, R2=R3=10kO. Find Vo when Q1 is OFF.
R4
VI



7.5 V b)5V c) 10V 8.33V
55 Assume that Vi 2V; R3 100; Pof Q1 50; Vee 15V. Find lout.
vee
vee Vi lout .U1
R3

3.92mA b)4mA c) 6.84mA 2.8mA
56 A sample and hold amplifier is connected to an ADC. The acquisition time of the sample and hold amplifier is 10 J.lsec and the conversion time of the ADC is 15 J.lsec. What is the highest possible data rate? 100 ksamples 400 ksamples 40 ksamples 66 ksamples


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2010 ELECTRONICS AND COMMUNICATION ENGINEERING SET-A
57 In an inverting OP-AMP, the input bias current is and the input and the feedback resistances are both What will be the output voltage for an input voltage of2.5V? -2.5V -3.0V -3.5V 4.0V
58 Which of the following devices can be used for generating a PWM signal? Comparator 555 timer Counter and magnitude comparator All the above
59 A microwave receiving antenna on a satellite is pointing towards the earth. The antenna beamwidth is 50 degrees. The earth subtends 5 degrees at the satellite. What will be the noise temperature of the antenna? 30 degrees Kelvin 5 degrees Kelvin 300 degrees Kelvin 1000 degrees Kelvin
60 Estimate the magnitude and phase of the element SI I of the S-matrix of the circuit shown below. Assume an operating frequency of25 MHz.
1k

50Q
10 uF

50Q
100 uF
I

25 L 1800 25 L 00 0.33·L 1800 0.33 L 00
61 The electric field measured in the far field of an antenna at a distance ofSOm is IV1m. The average power density at a distance of SOOm from the antenna is
2
26.6JlW/m2 0.lJlW/m2 lOJlW/m2 13.3,..,W/m
62 A quarter wave monopole antenna is situated above a perfectly conducting ground plane. It is driven by a SOV source at SOOMHz through an internal impedance of 63.5Q. The average power radiated by the antenna is
2
39.37W/m2 4.S6W/m2 68.49W/m2 4S.6W/m
Electronics and Communication Engineering

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63 Directional derivative of U=2x3y-3y2z at in a direction towards is 30/7 90/49 None of the above
64 Consider the equation where z is a complex number, c is a nonzero constant and Re( represents the real part. The equation describes a Straight line Parabola Circle None of the above
65 How many adders are required to realize a 256 point radix-2 FFT using decimation-in-time? 256 1024 4096 2048
66 A uniformly distributed random signal with mean mx=2 and variance
is passed through a 3-point moving-average filter having an impulse response yj,yj}. What will be the mean and variance of output? my my c)m d)m
y,y y,y
67 A sine wave is applied to a balanced modulator. The peak output envelope power is 1000 times the minimum output envelope power. Estimate the carrier suppression in dBc. a)24dBc b)30dBc 36dBc d)40dBc
68 Consider a single error correcting cyclic code with generator matrix x3 +x2+1. What will be the transmitted data if received vector r is 1101101? 1100 1010 0001 1110
69 Consider a Golay's code with t bits of error correction capability. For what value of t will the code exactly satisfy the Hamming bound? a)2 b)3 4 d)5
70 The maximum range of a monostatic Radar is R. If a target having a Radar cross­section of 10m2 exists at what should be the target cross-section at 3R/2 to result in an equal signal strength at the Radar?
2
90m2 b) 270W/m2 810m2 30W/m
71 The electric field intensity at a distance of 10km from an antenna having a directive gain of 10dB and radiating a total power of 60kW is
2
0.6V/m 1.2V/m 0.36V/m d) 13.3JlW/m
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What is the characteristic impedance of a coaxial transmission line having inner72
conductor radius of 1mm, outer conductor radius of 2mm and dielectric constant of 4.0? 50 ohm· 60 ohm 20.62 ohm • none
73 An impedance of -10 -j2 ohms is connected to another impedance of 45 j5 ohms
through a transmission line having a characteristic impedance of50 ohms. Assess the
stability of this circuit.

Highly stable
Stability cannot be determined from the given information
Highly unstable
Marginally unstable

74 A transmission line of characteristic impedance 75 ohms is terminated with an impedance of 50 ohms. The line length is increased from zero. What will be the locus of the input impedance at the other end of the line? (N.B. Reference impedance of Smith Chart 50 Ohms)


Locus [AJ Locus Locus Locus
75 The value of the integral Jsinz/ z3 .dz around the circle Izl=2 is
1 0 -112

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76 77 Which of the following functions have a jump discontinuity at x=O =In Ixl lIx2 SineX) 0 None of the above x X 0 What would be the output of the following circuit, if a positive going unipolar pulse with an amplitude greater than Vref, is applied at the input? R2 vee R1 01 a Via U1 au Va Vref

Vo will go high momentarily and return to low Vo will go low momentarily and return to high Vo will go high and remain high Vo will not change its previous state
78 What is the output voltage across the 900 ohm load in the circuit given below? 500 1K


10V 14.67V 20V 9.47 V

·18
79 What is the transfer function of the network given below? 1


VI
V2
1

+2s
80 A voltage regulator having Vref=1.25V needs to generate 5V output. Assume that Iadj 100,..,A and R1 10kohm. What should be value of R2?
U1
2
ViO---lIN


30 kohm 33.33 kohm 16.66kohm 22.22 kohm