Previous Year Questions
48 questions — organised by subject with solutions and explanations.
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A zener diode regulator in figure is to be designed to meet the specifications: and varies from 30 V to 50 V. The zener diode has = 10V and (knee current) = 1 mA. For satisfactory opertion
If the transistor in Figure is in saturation, then
In a negative feedback amplifier using voltage-series (i.e. voltage-sampling series mixing) feedback. (Ri and Ro denote the input and output resistance respectively)
The voltage gain of the JFET amplifier shown in figure 2.8 is
A 741-type op-amp has a gain-bandwidth product of 1 MHz. A non-inverting amplifier using this op-amp and having a voltage gain of 20 dB will exhibit a 3-dB bandwidth of
The circuit in figure employs positive feedback and is intended to generate sinusoidal oscillation. If at a frequency , then to sustain oscillation at this frequency
An amplifier using an opamp with a slew-rate SR = 1V/ sec has a gain of 40 dB. If this amplifier has to faithfully amplify sinusoidal signals from dc to 20 KHz without introducing any slew-rate induce
Consider the following statements in connection with the CMOS inverter in figure, where both the MOSFETs are of enhancement type and both have a thresh old voltage of 2V. Statement 1: T1 conducts when
Three identical RC-coupled transistor amplifiers are cascaded. If each of the amplifiers has a frequency response as shown in Figure, the overall frequency response is as given in
For a bit-rate of 8 Kbps, the best possible values of the transmitted frequencies in a coherent binary FSK system are
Consider a sample signal where and . When y(t) is passed through an ideal low-pass filter with a cutoff frequency of 5 KHz, the output of the filter is
An angle modulated signal is given by The maximum frequency and phase deviations of s(t) are
A 1 MHz sinusoidal carrier is amplitude modulated by a symmetrical square wave of period 100 sec. Which of the following frequencies will NOT be present in the modulated signal?
If the variance of d(n)=x(n)-x(n-1) is one-tenth the variance of a stationary zero mean discrete time signal x(n), then the normalized autocorrelation function at k=1 is
A signal is ideally sampled with a sampling period of 50 sec and then passed through an ideal low-pass filter with cutoff frequency of 15 KHz. Which of the following frequencies is/are present at the
In the figure, , and . The output y(t) will be
The system shown in figure remains stable when
Which of the following points is NOT on the root locus of a system with the open loop transfer function
The transfer function Y(s)U(s) of a system described by the state equations x(t) = -2x(t) + 2u(t) and y(t) = 0.5x(t) is
The phase margin of a system with the open-loop transfer function is
Consider a system with the transfer function . Its damping ratio will be 0.5 when the value of k is
The system with the open loop transfer function has a gain margin of
The transfer function of a system is . For a unit step input to the system the approximate settling time for 2% criterion is
The characteristic polynomial of a system is . The system is
4-bit 2's complement representation of a decimal number is 1000. The number is
The number of comparators required in a 3-bit comparator type ADC is
The circuit in figure has two CMOS NOR gates. This circuit functions as a:
If the input to the ROM in figure are 8-4-2-1 BCD numbers, then the outputs are
If the input to the digital circuit (shown in figure ) consisting of a cascade of 20 XOR gates is X, then the output Y is equal to
The gates G1 and G2 in figure have propagation delays of 10 nsec and 20 nsec respectively. If the input makes an abrupt change from logic 0 to 1 at time then the output waveform is
Distilled water at 25 C is characterized by = 1.7 mho/m and at a frequency of 3 GHz. Its loss tangent is ( F/m)
A plane wave is characterized by . This wave is
The phase velocity for the TE10-mode in an air-filled rectangular waveguide is (c is the velocity of plane waves in free space)
In an impedance Smith chart, a clockwise movement along a constant resistance circle gives rise to
The VSWR can have any value between
The electric field on the surface of a perfect conductor is 2 V/m. The conductor is immersed in water with . The surface charge density on the conductor is ( )
The dependent current source shown in Figure
If the 3-phase balanced source in figure delivers 1500 W at a leading power factor of 0.844, then the value of (in ohm) is approximately
In figure, the switch was closed for a long time before opening at t = 0. the voltage at t = is
In the network of figure, the maximum power is delivered to if its value is
A linear phase channel with phase delay and group delay must have
The Laplace transform of a continuous-time signal x(t) is . If the Fourier transform of this signal exists, then x(t) is
If the impulse response of a discrete-time system is , then the system function H(z) is equal to
Which of the following cannot be the Fourier series expansion of a periodic signal?
The Fourier transform is equal to . therefore, is
Convolution of x(t+5) with impulse function (t-7) is equal to