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GATE Electronics and Communication Test 3 Online Question Answers

Test Name GATE Electronics and Communication Test
Subject GATE
Test Type MCQs
Total Question 40
Total Marks 80
Total Time 40 Minutes
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The Graduate Aptitude Test in Engineering, GATE tests conduct for examinations various undergraduate subjects in engineering and science. Electronics and Communication engineering students studied in electronic devices, circuits, communication equipment related transmitter, receiver, and integrated circuits. For preparation purpose about entry test, jobs test, admissions test on concept of Electronics and Communications Engineering quiz are following.

GATE Electronics and Communication Online Test 3


1. A BPSK scheme operating over an AWGN channel with noise power spectral density of N/2, uses equiprobable signals s1(t) = √2E/T sin(ωct) and s2(t) = -√2E/T sin(ωct) over the symbol interval (0, T). If the local oscillator in a coherent receiver is ahead in phase by 45 with respect to the received signal, the probability of error in the resulting system is

Question 1 of 40

2. The unilateral Laplace transform of f(t) is 1/s² + s +1. The unilateral Laplace transform of tf(t) is.

Question 2 of 40

3. A transmission line with a characteristics impedance of 100Ω is used to match a 50Ω section to a 200Ω section. If the matching is to be done both at 429 MHz and 1 GHz, the length of the transmission line can be approximately:

Question 3 of 40

4. A source alphabet consists of N symbols with the probability of the first two symbols being the same. A source encoder increase the probability of the first symbol by a small amount ε. After encoding, the entropy of the source

Question 4 of 40

5. Assuming both the voltage sources are in phase, the value of R for which maximum power is transferred from circuit A to circuit B is:
Cir Q

Question 5 of 40

6. A plane wave propagating in air with E = (8âx + 6ây - 5âz) i(ωt + 3x – 4y) V/m is incident on a perfectly conducting slab positioned at x ≤ 0. The E field of the reflected wave is:

Question 6 of 40

7. The electric field of a uniform plane electromagnetic wave in free space, along the positive x direction, is given by E  = 10(ây + jâz) e-j25x. The frequency and polarization of the wave, respectively, are

Question 7 of 40

8. In the CMOS circuit shown, electron and hole mobilities are equal, and M1 and M2 are equally sized. The device M1is in the linear region if:

Question 8 of 40

9. A binary symmetric channel (BSC) has a transition probability of 1/8. If the binary transit symbol X is such that P(X = 0) = 9/10, then the probability of error for an optimum receiver will be:

Question 9 of 40

10. A fair coin is tossed till a head appears for the first time. The probability that the number of required tosses is odd, is:

Question 10 of 40

11. The output Y of a 2-bit comparator  is logic 1 whenever the 2 bit input A greater than the 2-bit input B. The number of combinations for which the output is logic 1, is:

Question 11 of 40

12. Given that
A = [-5      -3] and I = [1    0],  the value of A³ is:
2        0                  0    1

Question 12 of 40

13. In a baseband communications link, frequencies up to 3500 Hzare used for signalling. Using a raised cosine pulse with 75% excess bandwidth and for no inter-symbol interference, the maximum possible signalling rate in symbols per second is:

Question 13 of 40

14. The radiation pattern of an antenna in spherical co-ordinates is given by
F(θ) = cosθ; 0 ≤ θ ≤ π/2
The directivity of antenna is

Question 14 of 40

15. The impedance looking into nodes 1 and 2 in the given circuit is:

Question 15 of 40

16. A system with transfer function
G(s)  = (s² + 9)(s + 2)/(s + 1)(s + 3)(s + 4)
is excited by sin (ωt). The steady-state output of the system is zero at

Question 16 of 40

17. The maximum value of f(x) = x³ - 9x² + 24x + 5 in the interval [1, 6] is:

Question 17 of 40

18. With initial condition x(1) = 0.5, the solution of the differential equation t dx/dt is

Question 18 of 40

19. The feedback system shown below oscillates at 2 rad/s when

Question 19 of 40

20. The average power delivered to an impedance (4 - j3)Ω by a current 5 cos (100πt + 100)A is

Question 20 of 40

21. The vector of direction A is radially outward from the origin, with |A| = kr where r = x + y + z and k is a constant. The value of n for which ∇.A = 0 is

Question 21 of 40

22. In the circuit shown below, the current through the inductor is

Question 22 of 40

23. A coaxial cable with an inner diameter of 1 mm and outer diameter of 2.4 mm is filled with a dielectric of relative permitivity 10.89. Given μ0 = 4π x 10-7 H/m, ε = 10-9/36π F/m, the  characteristics impedance of the cable is

Question 23 of 40

24. The current ib through the base of a silicon npn transistor is 1 + 0.1 cos (1000πt) mA. At 300 K, the rπ in the small signal model of the transistor is:

Question 24 of 40

25. The signal m(t) as shown in applied both to a phase modulator (with kp as the phase constant) and a frequency modulator (with kr as the frequency constant) having the same carrier frequency
The ratio kp/kf (in rad /Hz) for the phase maximum phase deviation is:

Question 25 of 40

26. The diodes and capacitors in the circuit shown are ideal. The voltage v(t) across the diode D1 is

Question 26 of 40

27. The i-v characteristics of the diode in the circuit given below are:
The current in the circuit is:

Question 27 of 40

28. In the following figure, C1 and C2 are ideal capacitors. C1 has been charged to 12 V before the ideal switch S is closed at t = 0. The current i(t) for all t is

Question 28 of 40

29. The transfer function of a compensator is given as:
GC(s) = s+a/a+b
GC(s) = s+a/a+b compensator if

Question 29 of 40

30. The current shown is a:

Question 30 of 40

31. The input x(t) and output y(t) of a system are related as y(t) = ∫t-∞ x(τ)cos(3τ)dτ. The system is:

Question 31 of 40

32. The independent random variables X and Y are uniformly distributed in the interval [-1, 1]. The probability that max [X, Y] is less than 1/2 is:

Question 32 of 40

33. The power spectral density of a real process X(t) for positive frequencies is shown below. The values of E[X²(t)] and [E[X(t)]], respectively, are:

Question 33 of 40

34. In the circuit shown

Question 34 of 40

35. The voltage gain A of the current circuit shown below is:

Question 35 of 40

36. If VA - VB = 6V, then VC - VD is :

Question 36 of 40

37. If x[n] = (1/3)|n| - (1/2)n u[n], then the region of convergence (ROC) of its Z transformer in the Z-plane will be:

Question 37 of 40

38. The source of a silicon (ni =1010 per cm3) n-channel MOS transistor has an area of 1 sq μm and a depth of 1 Mm. If the dopant density in the source is 1019/cm3, the number of holes in the source region with the above volume is approximately

Question 38 of 40

39. The fourier transformer of a signal h(t) is H(jω) = (2 cosω) (sin 2ω)/ω. The value of h(0) is:

Question 39 of 40


40. The magnetic field along the propagation direction inside a rectangular waveguide with the cross section shown in the figure is
Hz = 3 cos (2.094 x 10²x) cos(2.618x10²y) cos(6.283x1010t - βz)
The phase velocity Vp of the wave inside the waveguide satisfies

Question 40 of 40


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