Previous Year Questions
63 questions — organised by subject with solutions and explanations.
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In the following transistor circuit =0.7V, , and and all the capacitances are very large The mid-band voltage gain of the amplifier is approximately
Consider the Schmidt trigger circuit shown below. A triangular wave which goes from -12 to 12 V is applied to the inverting input of OPMAP. Assume that the output of the OPAMP swings from +15 V to -15
In the following limiter circuit, an input voltage is applied. Assume that the diode drop is 0.7 V when it is forward biased. When it is forward biased. The zener breakdown voltage is 6.8 V The maximu
An astable multivibrator circuit using IC 555 timer is shown below. Assume that the circuit is oscillating steadily. The voltage across the capacitor varies between
Two identical NMOS transistors M1 and M2 are connected as shown below. is chosen so that both transistors are in saturation. The equivalent of the pair is defied to be at constant . The equivalent of
Consider the following circuit using an ideal OPAMP. The I-V characteristic of the diode is described by the relation where = 25 mV, = 1m A and V is the voltage across the diode (taken as positive for
The OPAMP circuit shown above represents a
For the circuit shown in the following figure, transistor M1 and M2 are identical NMOS transistors. Assume the M2 is in saturation and the output is unloaded. The current is related to as
Four messages band limited to W, W, 2W and 3W respectively are to be multiplexed using Time Division Multiplexing (TDM). The minimum bandwidth required for transmission of this TDM signal is
A speech signal, band limited to 4kHz and peak voltage varying between +5V and -5V, is sampled at the Nyquist rate. Each sample is quantized and represented by 8 bits. The number of quantization level
A memory less source emits n symbols each with a probability p. The entropy of the source as a function of n
Consider a Binary Symmetric Channel (BSC) with probability of error being p. To transmit a bit, say 1, we transmit a sequence of three 1s. The receiver will interpret the received sequence to represen
Noise with double-sided power spectral density on K over all frequencies is passed through a RC low pass filter with 3 dB cut-off frequency of . The noise power at the filter output is
The signal is
The probability density function (pdf) of random variable X is as shown below The corresponding commutative distribution function CDF has the form
Consider the amplitude modulated (AM) signal . For demodulating the signal using envelope detector, the minimum value of should be
is the probability density function for the real random variable X, over the entire x axis, M and N are both positive real numbers. The equation relating M and N is
Consider the frequency modulated signal with carrier frequency of Hz. The modulation index is
Step responses of a set of three second-order underdamped systems all have the same percentage overshoot. Which of the following diagrams represents the poles of the three systems ?
A certain system has transfer function , where is a parameter. Consider the standard negative unity feedback configuration as shown below Which of the following statements is true?
Group I gives two possible choices for the impedance Z in the diagram. The circuit elements in Z satisfy the conditions . The transfer functions represents a kind of controller. Match the impedances i
The number of open right half plane of is
Group I lists a set of four transfer functions. Group II gives a list of possible step response y(t). Match the step responses with the corresponding transfer functions.
The magnitude of frequency responses of an underdamped second order system is 5 at 0 rad/sec and peaks to at 5 rad/sec. The transfer function of the system is
A signal flow graph of a system is given below. The set of equalities that corresponds to this signal flow graph is
Consider the matrix . Thr value of is
A linear, time - invariant, causal continuous time system has a rational transfer function with simple poles at s =- 2 and s =- 4 and one simple zero at s =- 1 . A unit step u(t) is applied at the inp
For the circuit shown in the figure, D has a transition from 0 to 1 after CLK changes from 1 to 0. Assume gate delays to be negligible. Which of the following statements is true
For the circuit shown in the following, are inputs to the 4:1 multiplexers, R(MSB) and S are control bits. The output Z can be represented by
The logic function implemented by the following circuit at the terminal OUT is
The two numbers represented in signed 2's complement form are P = 11101101 and Q = 11100110. If Q is subtracted from P, the value obtained in signed 2's complement is
In the following circuit, the comparator output is logic "1" if and is logic "0" otherwise. The D/A conversion is done as per the relations Volts, where (MSB), , , (LSB) are the counter outputs. The c
For each of the positive edge-triggered J-K flip flop used in the following figure, the propagation delay is T. Which of the following wave forms correctly represents the output at ?
Which of the following Boolean Expressions correctly represents the relation between P,Q,R and
A uniform plane wave in the free space is normally incident on an infinitely thick dielectric slab (dielectric constant =9). The magnitude of the reflection coefficient is
In the design of a single mode step index optical fibre close to upper cut-off, the single-mode operation is not preserved if
For static electric and magnetic fields in an inhomogeneous source-free medium, which of the following represents the correct form of Maxwell's equations ?
A rectangular waveguide of internal dimensions (a=4cm and b=3cm) is to be operated in mode. The minimum operating frequency is
One end of a loss-less transmission line having the characteristic impedance of 75 and length of 1 cm is short-circuited. At 3 GHz, the input impedance at the other end of transmission line is
A silicon wafer has 100 nm of oxide on it and is furnace at a temperature above C for further oxidation in dry oxygen. The oxidation rate
Consider the following assertions. S1 : For Zener effect to occur, a very abrupt junction is required. S2 : For quantum tunneling to occur, a very narrow energy barrier is required. Which of the follo
The cross section of a JFET is shown in the following figure. Let be -2V and let be the initial pinch -off voltage. If the width W is doubled (with other geometrical parameters and doping levels remai
The drain current of MOSFET in saturation is given by where K is a constant. The magnitude of the transconductance is
The measured trans conductance of an NMOS transistor operating in the linear region is plotted against the gate voltage at a constant drain voltage . Which of the following figures represents the expe
Which of the following is NOT associated with a p-n junction ?
Which of the following is true?
Silicon is doped with boron to a concentration of atoms/ . Assume the intrinsic carrier concentration of silicon to be and the value of kT/q to be 25 mV at 300 K. Compared to undopped silicon, the fer
The Thevenin equivalent impedance between the nodes P and Q in the following circuit is
A two-port network shown below is excited by external dc sources. The voltages and the currents are measured with voltmeters and ammeter (all assumed to be ideal), as indicated. Under following switch
In the following graph, the number of trees (P) and the number of cut-set (Q) are
In the following circuit, the switch S is closed at t = 0. The rate of change of current is given by
The following series RLC circuit with zero initial conditions is excited by a unit impulse function For , the voltage across the resistor is
The circuit shown in the figure is used to charge the capacitor C alternately from two current sources as indicated. The switches and are mechanically coupled and connected as follows: For 2nT t (2n+1
The driving point impedance of the following network is given by The component values are
Let x(t) be the input and y(t) be the output of a continuous time system. Match the system properties P1, P2 and P3 with system relations R1, R2, R3,R4
In the following network, the switch is closed at t= and the sampling starts from t=0. The sampling frequency is 10Hz. The expression and the region of convergence of the z-transform of the sampled si
The impulse response h(t) of a linear time invariant continuous time system is described by h(t) = exp( t)u(t) + exp( t)u(-t), where u(-t) denotes the unit step function, and and are real constants. T
{x(n)} is a real-valued periodic sequence with a period N. x(n) and X(k) form N-point Discrete Fourier Transform (DFT) pairs. The DFT Y(k) of the sequence is
The signal x(t) is described by Two of the angular frequencies at which its Fourier transform becomes zero are
The input and output of a continuous time system are respectively denoted by x(t) and y(t). Which of the following descriptions corresponds to a causal system ?
The impulse response h(t) of a linear time invariant continuous time system is given by h(t)=exp(-2t)u(t), where u(t) denotes the unit step function The output of this system, to the sinusoidal input
A discrete time linear shift-invariant system has an impulse response h[n] with h[0]=1, h[1]=-1, h[2]=2, and zero otherwise The system is given an input sequence x[n] with x[0]=x[2]=1, and zero otherw