Company: DRDO

1.A negative feedback is applied to an amplifier with the feedback voltage proportional to the output current. This feedback increases the
a) input impedance of the amplifier b) output impedance of the amplifier c) distortion in the amplifier d) gain of the amplifier

2.The early effect in a BJT is modeled by the small signal parameter
a) r0 b) r? c) gm d) ß

3.For a given filter order, which one of the following type of filters has the least amount of ripple both in pass-band and stop-band?
a) Chebyshev type I b) Bessel c) Chebyshev type II d) Elliptic

4.For a practical feedback circuit to have sustained oscillation, the most appropriate value of the loop gain T is
a) 1 b) -1 c) -1.02 d) 1.02

5.Assume the op-amps in given figure to be ideal. If the input signal vi is a sinusoid of 2V peak-to-peak and with zero DC component, the output signal vo is a
a) sine wave b) square wave c) pulse train d) triangular wave

6.In a common source amplifier, the mid-band voltage gain is 40 dB and the upper cutoff frequency is 150kHz. Assuming single pole approximation for the amplifier the unity gain frequency fT is
a) 6 MHz b) 15 MHz c) 150 MHz d) 1.5 GHz

7.An op-amp is ideal except for finite gain and CMRR. Given the open loop differential gain Ad=2000, CMRR = 1000, the input to the noninverting terminal is 5.002 V and the input to the inverting terminal is 4.999 V, the output voltage of the op-amp is
a) 14 V b) 24 V c) -6 V c) -8 V

8.The op-amp in the circuit in given figure has a non-zero DC offset. The steady state value of the output voltage Vo is
a) –RC dvs(t)/ dt b) – (1/RC)|vs(t)dt c) –V d) +V

9.For the circuit in given figure, if the value of the capacitor C is doubled, the duty-cycle of the output waveform Vo
a) increases by a factor of 2 b) increases by a factor of 1.44 c) remains constant d) decreases by a factor of 1.44

10.Assume the op-amp in the given circuit to be ideal. The value of the output voltage Vo is
a) 3.2 Vi b) 4 Vi c) 9 Vi d) 10 Vi

11.The complement of the Boolean expression F = (X + Y¯ + Z)(X¯ + Z¯)(X + Y) is
a) XYZ+XZ¯+Y¯Z b) X¯YZ¯+XZ+X¯Y¯ c) X¯YZ¯+XZ+YZ d) XYZ+X¯Y¯

12.The Boolean function F(A,B,C,D) = ?(0,6,8,13,14) with don’t care conditions d(A,B,C,D) = ?(2,4,10) can be simplified to
a) F = B¯D¯+CD¯+ABC¯ b) F = B¯D¯+CD¯+ABC¯D c) F = AB¯D¯+CD¯+ABC¯ d) F = B¯D¯+CD¯+ABCD

13.The Boolean function F = A¯D¯+B¯D can be realized by one of the following figures

14. For the multiplexer in given figure, the Boolean expression for the output Y is
a) A¯B¯+B¯C¯+AC b) AB¯+B¯C¯+AC¯ c) AB¯+B¯C+AC d) A¯B¯+B¯C+A¯C

15. Which one of the following is TRUE?
a) Both latch and flip-flop are edge triggered.
b) A latch is level triggered and a flip-flop is edge triggered.
c) A latch is edge triggered and a flip-flop is level triggered.
d) Both latch and flip-flop are level triggered.

16. In a schottky TTL gate, the Schottky diode
e) increases the propagation delay
f) increases the power consumption
g) prevents saturation of the output transistor
h) keeps the transistor in cutoff region

17. For which one of the following ultraviolet light is used to erase the stored contents

18. Which one of the following is NOT a synchronous counter
a) Johnson counter b) Ring counter c) Ripple counter d) Up-down counter

19. In 8085 microprocessor, the accumulator is a
a) 4 bit register b) 8 bit register c) 16 bit register d) 32 bit register

20. In the register indirect addressing mode of 8085 microprocessor, data is stored
a) at the address contained in the register pair
b) in the register pair
c) in the accumulator
d) in a fixed location of the memory

21. The output w[n] of the system shown in given figure is
a) x[n] b) x[n-1] c) x[n] – x[n-1] d) 0.5(x[n-1] + x[n])

22. Which one of the following is a periodic signal
a) x(t) = 2 e^j(t+(p/4)) b) x[n] = u[n] + u[-n] c) x[n] = ?{?[n-4k]-?[n-1-4k]} where k = -8to 8 d) x(t) = e^ (-1+j)t

23. If the input-output relation of a system is y(t) = ?x(t) dt where t = -8 to 2t
a) linear, time-invariant and unstable
b) linear, non-causal and unstable
c) linear, causal and time invariant
d) non-causal, time invariant and unstable

24. Which one of the can be the magnitude of the transfer function | H(jw) | of a causal system

25. Consider the function H(jw) = H1(w) + jH2(w), where H1(w) is an odd function and H2(w) is an even function. The inverse Fourier transform of H(jw) is
a) a real and odd function
b) a complex function
c) a purely imaginary function
d) a purely imaginary and odd function

26. The laplace transform of given signal is
a) –A((1-e^cs)/s) b) A((1-e^cs)/s) c) A((1-e^-cs)/s) d) –A((1-e^-cs)/s)

27. If X(z) is the z-transform of x[n] = (1/2)^ |n|, the ROC of X(z) is
a) |z| > 2 b) |z| < 2 c) 0.5<|z|<2 d) the entire z-plane 28. In a linear phase system, tg the group delay and tp the phase delay are a) constant and equal to each other b) tg is a constant and tp is proportional to w c) a constant and tg is proportional to w d) tg is proportional to w and tp is proportional to w 29. A signal m(t), band-limited to a maximum frequency of 20 kHz is sampled at a frequency fs kHz to generate s(t). An ideal low pass filter having cut-off frequency 37 kHz is used to reconstruct m(t) from s(t). The maximum value of fs required to reconstruct m(t) without distortion is a) 20 kHz b) 40kHz c) 57 kHz d) 77 kHz 30. If the signal x(t) shown in given figure is fed to an LTI system having impulse response h(t) as shown in given figure, the value of the DC component present in the output y(t) is a) 1 b) 2 c) 3 d) 4 31. The characteristic equation of an LTI system is given as s^3 + Ks^2 + 5s + 10. When the system is marginally stable, the value of K and the sustained oscillation frequency w, respectively, are a) 2 and 5 b) 0.5 and v5 c) 0.5 and 5 d) 2 and v5 32. The time required for the response of a linear time-variant system to reach half the final value for the first time is a) delay time b) peak time c) rise time d) decay time 33. The signal flow graph of the given network is 34. Let c(t) be the unit step response of a system with transfer function K(s+a)/(s+K). If c(0+)=2 and c(8)=10, then the values of a and K, respectively, are a) 2 and 10 b) -2 and 10 c) 10 and 2 d) 2 and -10 35. The loop transfer function of an LTI system is G(s)H(s)= K(s+1)(s+5) / s(s+2)(s+3). For K>0, the point on the real axis that DOES NOT belong to the root locus of the system is
a) -0.5 b) -2.5 c) -3.5 d) -5.5