Previous Year Questions
1 paper · 45 questions — organised by subject with solutions and explanations.
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In the circuit shown below, assume that the voltage drop across a forward biased diode is 0.7 V. The thermal voltage . The small signal input where . The ac output voltage is
In the circuit shown below, capacitors C1 and C2 are very large and are shorts at the input frequency. is a small signal input. The gain magnitude at 10 M rad/s is
For the BJT in the circuit shown below, . The switch is initially closed. At time t=0, the switch is opened. The time t at which leaves the active region is
In the circuit shown below, for the MOS transistors, and the threshold voltage = 1V. The voltage at the source of the upper transistor is
The circuit below implements a filter between the input current and the output voltage . Assume that the opamp is ideal. The filter implemented is a
A message signal modulates the carrier where =1MHz to produce an AM signal. For demodulating the generated AM signal using an envelope detector, the time constant RC of the detector circuit should sat
X(t) is a stationary random process with auto-correlation function . This process is passed through the system shown below. The power spectral density of the output process Y(t) is
A four-phase and an eight-phase signal constellation are shown in the figure below. Assuming high SNR and that all signals are equally probable, the additional average transmitted signal energy requir
The Column-I lists the attributes and the Column-II lists the modulation systems. Match the attribute to the modulation system that best meets it
An analog signal is band-limited to 4 kHz, sampled at the Nyquist rate and the samples are quantized into 4 levels. The quantized levels are assumed to be independent and equally probable. If we trans
The input-output transfer function of a plant . The plant is placed in a unity negative feedback configuration as shown in the figure below. The signal flow graph that DOES NOT model the plant transfe
The differential equation describes a system with an in put x(t) and an output y(t). The system, which is initially relaxed, is excited by a unit step input. The output y(t) can be represented by the
For the transfer function , the corresponding Nyquist plot for positive frequency has the form
The block diagram of a system with one input it and two outputs is given below. A state space model of the above system in terms of the state vector and the output vector is
The input-output transfer function of a plant . The plant is placed in a unity negative feedback configuration as shown in the figure below. The gain margin of the system under closed loop unity negat
The root locus plot for a system is given below. The open loop transfer function corresponding to this plot is given by
The output of a 3-stage Johnson (twisted ring) counter is fed to a digital-to analog (D/A) converter as shown in the figure below. Assume all the states of the counter to be unset initially. The wavef
When the output Y in the circuit below is '1', it implies that data has
The output Y in the circuit below is always '1' when
The logic function implemented by the circuit below is (ground implies logic 0)
Two D flip-flops are connected as a synchronous counter that goes through the following sequence 00 11 01 10 00 .... The combination to the inputs are
A current sheet = 10 A/m lies on the dielectric interface between two dielectric media with =5, =1 in Region-1 and =5, =2 in Region-2 . If the magnetic field in Region-1 at is + 30 A/m. The magnetic f
A transmission line of characteristic impedance 50 W is terminated by a 50 load. When excited by a sinusoidal voltage source at 10 GHz, the phase difference between two points spaced 2 mm apart on the
A transmission line of characteristic impedance 50 is terminated in a load impedance . The VSWR of the line is measured as 5 and the first of the voltage maxima in the line is observed at a distance o
The modes in a rectangular waveguide are denoted by where m and n are the eigen numbers along the larger and smaller dimensions of the waveguide respectively. Which one of the following statements is
The electric and magnetic fields for a TEM wave of frequency 14 GHz in a homogeneous medium of relative permittivity er and relative permeability =1 are given by Assuming the speed of light in free sp
Drift current in the semiconductors depends upon
The channel resistance of an N-channel JFET shown in the figure below is 600 when the full channel thickness ( ) of 10 is available for conduction. The built-in voltage of the gate junction ( ) is -1
A Zener diode, when used in voltage stabilization circuits, is biased in
A silicon PN junction is forward biased with a constant current at room temperature. When the temperature is increased by C, the forward bias voltage across the PN junction
For a BJT the common base current gain = 0.98 and the collector base junction reverse bias saturation current . This BJT is connected in the common emitter mode and operated in the active region with
In the circuit shown below, the value of such that the power transferred to is maximum is
In the circuit shown below, the network N is described by the following Y matrix: . The voltage gain is
In the circuit shown below, the initial charge on the capacitor is 2.5 mC, with the voltage polarity as indicated. The switch is closed at time = 0. The current at a time after the switch is closed is
The circuit shown below is driven by a sinusoidal input . The steady state output
In the circuit shown below, the Norton equivalent current in amperes with respect to the terminals P and Q is
In the circuit shown below, the current I is equal to
The first six points of the 8-point DFT of a real valued sequence are 5, 1-j3, 0, 3-j4, 0 and 3+j4. The last two points of the DFT are respectively
The trigonometric Fourier series of an even function does not have the
Two systems and are connected in cascade as shown below. The overall output is the same as the input with a one unit delay. The transfer function of the second system is
An input x(t)=exp(-2t)u(t)+ (t-6) is applied to an LTI system with impulse response h(t)=u(t). The output is
If the unit step response of a network is , then its unit impulse response is
A system is defined by its impulse response . The system is
If then the initial and final values of are respectively