Previous Year Questions
67 questions — organised by subject with solutions and explanations.
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Consider the Op-Amp circuit shown in the figure. If and , then the minimum and maximum values of (in radians) are respectively
For the Op-Amp circuit shown in the figure, is
For the Zener diode shown in the figure, the Zener voltage at knee is 7 V, the knee current is negligible and the Zener dynamic resistance is 10 . If the input voltage ( ) range is from 10 to 16 V, th
In the CMOS inverter circuit shown, if the trans conductance parameters of the NMOS and PMOS transistors are and their threshold voltages are , the current is
Consider the Op-Amp circuit shown in the figure. The transfer function is
The DC current gain ( ) of a BJT is 50. Assuming that the emitter injection efficiency is 0.995, the base transport factor is
In the Op-Amp circuit shown, assume that the diode current follows the equation . For , and for . The relationship between and is:
The correct full wave rectifier circuit is
In a transconductance amplifier, it is desirable to have
For the BJT circuit shown, assume that the of the transistor is very large and = 0.7V. The mode of operation of the BJT is
If is the auto correlation function of a real, wide-sense stationary random process, then which of the following is NOT true
Two 4-ray signal constellations are shown. It is given that and constitute an orthonormal basis for the two constellations. Assume that the four symbols in both the constellations are equiprobable. Le
If S(f) is the power spectral density of a real, wide-sense stationary random process, then which of the following is ALWAYS true?
An input to a 6-level quantizer has the probability density function f(x) as shown in the figure. Decision boundaries of the quantizer are chosen so as t maximize the entropy of the quantizer output.
If E denotes expectation, the variance of a random variable X is given by
In a Direct Sequence CDMA system the chip rate is chips per second. If the processing gain is desired to be AT LEAST 100, the data rate
Three functions f1(t), f2(t) and f3(t), which are zero outside the interval [0, T], are shown in the figure. Which of the following statements is correct?
During transmission over a certain binary communication channel, bit errors occur independently with probability p. The probability of AT MOST one bit in error in a block of n bits is given by
In the following scheme, if the spectrum M(f) of m(t) is as shown, then the spectrum Y(f) of y(t) will be
In a GSM system, 8 channels can co-exist in 200 kHz bandwidth using TDMA. A GSM based cellular operator is allocated 5 MHz bandwidth. Assuming a frequency reuse factor of , i.e. a five-cell repeat pat
In delta modulation, the slope overload distortion can be reduced by
The raised cosine pulse p(t) is used for zero ISI in digital communications. The expression for p(t) with unity roll-off factor is given by . The value of p(t) at is
A control system with PD controller is shown in the figure. If the velocity error constant =1000 and the damping ratio =0.5, then the value of and are
The asymptotic Bode plot of a transfer function is as shown in the figure. The transfer function G(s) corresponding to this Bode plot is
Consider a linear system whose state space representation is . If the initial state vector of the system is , then the system response is If the initial state vector of the system changes to , then th
The state space representation of a separately excited DC servo motor dynamics is given as where is the speed of the motor, is the armature current and u is the armature voltage. The transfer function
The transfer function of a plant is The second-order approximation of T(s) using dominant pole concept is
A unity feedback control system has an open-loop transfer function The gain K for which will lie on the root locus of this system is
If the closed-loop transfer function of a control system is given as , then it is
Consider a linear system whose state space representation is . If the initial state vector of the system is , then the system response is If the initial state vector of the system changes to , then th
The open-loop transfer function of a plant is given as . If the plant is operated in a unity feedback configuration, then the lead compensator that an stabilize this control system is
The frequency response of a linear, time-invariant system is given by . The step response of the system is
X = 01110 and Y =11001 are two 5-bit binary numbers represented in two's complement format. The sum of X and Y represented in two's complement format using 6 bits is
In the following circuit, X is given by
The circuit diagram of a standard TTL NOT gate is shown in the figure. , the modes of operation of the transistors will be
The Boolean expression can be minimized to
In the Digital-to-Analog converter circuit shown in the figure below, and R = 10K The voltage is
The following binary values were applied to the X and Y inputs of NAND latch shown in the figure in the sequence indicated below : X=0, Y=1; X=0, Y=0; X=1, Y=1. The corresponding stable P,Q output wil
For the circuit shown, the counter state ( ) follows the sequence
The Boolean function Y = AB + CD is to be realized using only 2-input NAND gates. The minimum number of gates required is
The parallel branches of a 2-wire transmission line re terminated in 100 and 200 resistors as shown in the figure. The characteristic impedance of the line is and each section has a length of . The vo
If C is closed curve enclosing a surface , then the magnetic field intensity , the current density and the electric flux density are related by
A right circularly polarized (RCP) plane wave is incident at an angle to the normal, on an air-dielectric interface. If the reflected wave is linearly polarized, the relative dielectric constant is.
The field (in A/m) of a plane wave propagating in free space is given by . The time average power flow density in Watts is
A plane wave of wavelength is traveling in a direction making an angle with positive x-axis and with positive y-axis. The field of the plane wave can be represented as ( is constant)
A load of 50 is connected in shunt in a 2-wire transmission line of as shown in the figure. The 2-port scattering parameter matrix (s-matrix) of the shunt element is
The field in a rectangular waveguide of inner dimension is given by where is a constant, and a and b are the dimensions along the x-axis and the y-axis respectively. The mode of propagation in the wav
An air-filled rectangular waveguide has inner dimensions of 3cm x 2cm. The wave impedance of the TE20 mode of propagation in the waveguide at a frequency of 30 GHz is (free space impedance = 377 )
A junction has a built-in potential of 0.8 V. The depletion layer width a reverse bias of 1.2 V is 2 . For a reverse bias of 7.2 V, the depletion layer width will be
Group I lists four different semiconductor devices. match each device in Group I with its charactecteristic property in Group II
The electron and hole concentrations in an intrinsic semiconductor are per at 300 K. Now, if acceptor impurities are introduced with a concentration of per (where ), the electron concentration per at
Group I lists four types of p-n junction diodes. Match each device in Group I with one of the option in Group II to indicate the bias condition of the device in its normal mode of operation.
The figure shows the high-frequency capacitance-voltage (C-V) characteristics of a Metal/ /silicon (MOS) capacitor having an area of Assume that the permittivities ( ) of silicon and SiO2 are F/cm and
In a n junction diode under reverse biased the magnitude of electric field is maximum at
An 8255 chip is interfaced to an 8085 microprocessor system as an I/O mapped I/O as show in the figure. The address lines of the 8085 are used by the 8255 chip to decode internally its thee ports and
An 8085 assembly language program is given below. Line 1: MVI A, B5H 2: MVI B, 0EH 3: XRI 69H 4: ADD B 5: ANI 9BH 6: CPI 9FH 7: STA 3010H 8: HLT After execution of line 7 of the program, the status of
In the ac network shown in the figure, the phasor voltage (in Volts) is
An independent voltage source in series with an impedance , delivers a maximum average power to a load impedance when
In the circuit shown, is 0 volts at t = 0 sec. For , the capacitor current , where t is in seconds is given by
For the circuit shown in the figure, the Thevenin voltage and resistance looking into X-Y are
The RC circuit shown in the figure is
Two series resonant filters are as shown in the figure. Let the 3-dB bandwidth of Filter 1 be and that of Filter 2 be . The value is
A Hilbert transformer is a
The 3-dB bandwidth of the low-pass signal u(t), where u(t) is the unit step function, is given by
The z-transform X[z] of a sequence x[n] is given by . It is given that the region of convergence of X[z] includes the unit circle. The value of x[0] is
A 5-point sequence x[n] is given as x[-3]=1, x[-2]=1, x[-1]=0, x[0]=5 and x[1]=1. Let denoted the discrete-time Fourier transform of x[n]. The value of is
If the Laplace transform of a signal y(t) is , then its final value is