1
The output V
0 of the diode circuit shown in the figure is connected to an averaging DC voltmeter. The reading on the DC voltmeter in Volts, neglecting the voltage drop across the
diode, is ____________.

2
In the circuit shown, transistors Q
1 and Q
2 are biased at a collector current of 2.6 mA.
Assuming that transistor current gains are sufficiently large to assume collector current equal
to emitter current and thermal voltage of 26m V, the magnitude of voltage gain V
o/V
s
in the
mid-band frequency range is _____________ (up to second decimal place).
3
In the voltage reference circuit shown in the figure, the op-amp is ideal and the transistors Q
1,
Q
2,….., Q
32 are identical in all respects and have infinitely large values of common – emitter
current gain $$\beta $$. The collector current (I
C) of the transistors is related to their base emitter voltage (V
BE) by the relation I
C = I
S exp (V
BE/V
T); where I
s is the saturation current. Assume that the
voltage V
P shown in the figure is 0.7 V and the thermal voltage V
T=26mV
The output voltage Vout (in volts) is _____.
4
Which one of the following graphs shows the Shannon capacity (channel capacity) in bits of a memory less binary symmetric channel with crossover probability P?
5
A sinusoidal message signal is converted to a PCM signal using a uniform quantizer. The required signal to quantization noise ratio (SQNR) at the output of the quantizer is 40dB. The minimum number of bits per sample needed to achieve the desired SQNR is ________ .
6
Consider a binary memoryless channel characterized by the transition probability diagram shown in the figure.

The channel is
7
Consider the random process
x(t) = U + Vt.
Where U is a zero mean Gaussian random variable and V is a random variable uniformly distributed between 0 and 2. Assume that U and V are statistically independent. The mean value of the random process at t = 2 is _________________
8
The un-modulated carrier power in an AM transmitter is 5kW. This carrier is modulated by a
sinusoidal modulating signal. The maximum percentage of modulation is 50%. If it is reduced
to 40%, then the maximum un-modulated carrier power (in kW) that can be used without
overloading the transmitter is ___________
9
A modulating signal given By $$x\left(t\right)=5\sin\left(4\mathrm\pi10^3\mathrm t\;-\;10\mathrm{πcos}2\mathrm\pi10^3\mathrm t\right)$$ V
is fed to a phase modulator
with phase deviation constant kp=0.5rad/V. If the carrier frequency is 20 kHz, the
instantaneous frequency (in kHz) at t = 0.5 ms is __________
10
For the system shown in the figure, Y (s) / X (s) = __________.

11
A unity feedback control system is characterized by the open-loop transfer function
$$$G\left(s\right)\;=\;\frac{2\left(s+1\right)}{s^3+ks^2+2s+1}$$$
The value of k for which the system oscillates at 2 rad/s is ________.
12
A unity feedback control system is characterized by the open loop transfer function
$$G(s) = {{10k\left( {s + 2} \right)} \over {\left( {{s^3} + 3{s^2} + 10} \right)}}$$
The Nyquist path and the corresponding Nyquist plot of g(s) are shown in the figures below.

If 0 < K < 1, then number of poles of the closed loop transfer function that lie in the right half of the s-plane is
13
Which of the following statement is incorrect?
14
A second order LTI system is described by the following state equation.
$$$\eqalign{
& {d \over {dt}}{x_1}\left( t \right) - {x_2}\left( t \right) = 0 \cr
& {d \over {dt}}{x_2}\left( t \right) + 2{x_1}\left( t \right) + 3{x_2}\left( t \right) = r\left( t \right) \cr} $$$
When x1(t) and x2(t) are the two state variables and r(t) denotes the input. The output c(t)=X1(t). The systyem is
15
Consider the state space realization
$$$\left[ {\matrix{
{\mathop x\limits^ \bullet } & {\left( t \right)} \cr
{\mathop x\limits^ \bullet } & {\left( t \right)} \cr
} } \right] = \left[ {\matrix{
0 & 0 \cr
0 & { - 9} \cr
} } \right]\left[ {\matrix{
{{x_1}} & {\left( t \right)} \cr
{{x_2}} & {\left( t \right)} \cr
} } \right] + \left[ {\matrix{
0 \cr
{45} \cr
} } \right]u\left( t \right),$$$ with the initial condition $$\left[ {\matrix{
{{x_1}} & {\left( 0 \right)} \cr
{{x_2}} & {\left( 0 \right)} \cr
} } \right] = \left[ {\matrix{
0 \cr
0 \cr
} } \right];$$
Where u(t) denotes the unit step function.
The value of $$\mathop {Lt}\limits_{x \to \infty } \left| {\sqrt {{x_1}^2\left( t \right) + {x_2}^2\left( t \right)} } \right|$$ is ______
16
The state diagram of a finite state machine (FSM) designed to detect an overlapping sequence of three bits is shown in the figure. The FSM has an input 'In' and an output 'Out'. The initial state of the FSM is S
0.
If the input sequence is 10101101001101, starting with the left-most bit, then the number of times 'Out' will be 1 is __________.
18
Consider the circuit shown in the figure.

The Boolean expression F implemented by the circuit is
19
A programmable logic array (PLA) is shown in the figure.

The Boolean function F implemented is
20
Figure I shows a 4-bits ripple carry adder realized using full adders and Figure II shows the circuit of a full-adder (FA). The
propagation delay of the XOR, AND and OR gates in Figure II are 20 ns, 15 ns and 10 ns respectively. Assume all the inputs to
the 4-bit adder are initially reset to 0.

At t=0, the inputs to the 4-bit adder are changed to $${X_3}$$$${X_2}$$$${X_1}$$$${X_0}$$ =1100, $${Y_3}$$$${Y_2}$$$${Y_1}$$$${Y_0}$$ = 0100 and $${Z_0}$$=1.
The output of the ripple carry adder will be stable at t (in ns) = ____
21
A two wire transmission line terminates in a television set. The VSWR measured on the line is 5.8. The percentage of power that is reflected from the television set is
22
Standard air filled rectangular waveguides of dimensions a = 2.29cm and b = 1.02cm are designed for radar applications. It is desired that these waveguides operate only in the dominant $$T{E_{10}}$$ mode with the operating frequency at least 25% above the cut-off frequency of the $$T{E_{10}}$$ mode but not higher than 95% of the next higher cutoff frequency. The range of the allowable operating frequency f is
23
The permittivity of water at optical frequencies is $$1.75{\varepsilon _0}$$. It is found that an isotropic light source at a distance d under water forms an illuminated circular area of radius $$5m$$, as shown in the figure. The critical angle is $${\theta _c}$$
The value of $$d$$ (in meter) is ______ .
24
Two conducting spheres S1 and S2 of radii a and b (b>a) respectively, are placed far apart and
connected by a long, thin conducting wire, as shown in the figure.
For some charge placed on this structure, the potential and surface electric field on S1 are Va
and Ea
, and that on S2 are Vb and Eb, respectively, which of the following is CORRECT?
25
An electron (q
1) is moving in free space with velocity 10
5 m/s towards a stationary electron
(q
2) far away. The closest distance that this moving electron gets to the stationary electron
before the repulsive force diverts its path is ___________ ×10
-8m.
[Given, mass of electron m = 9.11×10-31 kg, charge of electron e = -1.6×10-19 C , and
permittivity $$\varepsilon_0=\left(1/36\mathrm\pi\right)\times10^{-9}\;\mathrm F/\mathrm m$$].
26
An n-channel enhancement mode MOSFET is biased at VGS > VTH and VDS > (VGS - VTH), where
VGS is the gate-to-source voltage, VDS is the drain-to-source voltage and VTH is the threshold
voltage. Considering channel length modulation effect to be significant, the MOSFET behaves
as a
27
For a particular intensity of incident light on a silicon pn junction solar cell, the photocurrent
density (JL) is 2.5 mA/cm2
and the open-circuit voltage (V$$_{oc}$$) is 0.451 V. consider thermal
voltage (V$$_T$$) to be 25 mV. If the intensity of the incident light is increased by 20 times,
assuming that the temperature remains unchanged. V$$_{oc}$$ (in volts) will be ______.
28
An npn bipolar junction transistor (BJT) is operating in the active region. If the reverse bias
across the base-collector junction is increased, then
29
Consider the circuit shown in the figure. Assume base-to-emitter voltage V
BE=0.8 V and common base current gain $$\left(\alpha\right)$$ of the transistor is unity.

The value of the collector-to–emitter voltage V
CE (in volt) is _______.
30
Consider an n-channel MOSFET having width W, length L, electron mobility in the channel
$$\mu_n$$ and oxide capacitance per unit area $$C_{ox}$$. If gate-to-source voltage VGS=0.7 V, drain-to source
voltage VDS=0.1V, $$\left(\mu_nC_{ox}\right)\;=\;100\;\mu A/V^2$$, threshold voltage VTH=0.3 V and (W/L) = 50,
then the transconductance gm (in mA/V) is ___________.
31
For the circuit shown in the figure, P and Q are the inputs and Y is the output.

The logic implemented by the circuit is
32
Two n-channel MOSFETs, T1 and T2, are identical in all respects except that the width of T2 is double of T1. Both the transistor are biased in the saturation region of operation, but the gate overdrive voltage (VGS - VTH) of T2 is double that of T1, where VGS and VTH are the gate-to-source voltage and threshold voltage of the transistors, respectively. If the drain current and transconductance of T1 are ID1 and gm1 respectively ; the corresponding values of these two parameters for T2 are
33
Assuming that transistor M
1 and M
2 are identical and have a threshold voltage of 1V, the state of transistors M
1 and M
2 are respectively
34
A MOS capacitor is fabricated on p-type Si (silicon) where the metal work function is 4.1 eV
and electron affinity of Si is 4.0 eV, Ec - EF = 0.9 eV; where Ec and EF are conduction band minimum and the Fermi energy levels of Si, respectively. Oxide$${\varepsilon _r} = \,\,3.9,\,\,\,{\varepsilon _{0\,\,}}=\,8.85 \times {10^{ - 14}}$$ F/cm, oxide thickness $${t_{ox}} = 0.1\,\mu m$$
and electronic charge q = $$1.6 \times {10^{ - 19}}$$ C. If the measured flat band
voltage of the capacitor is –1V, then the magnitude of the fixed charge at the oxide semiconductor
interface, in nC/cm2, is __________.
35
The rank of the matrix $$\left[ {\matrix{
1 & { - 1} & 0 & 0 & 0 \cr
0 & 0 & 1 & { - 1} & 0 \cr
0 & 1 & { - 1} & 0 & 0 \cr
{ - 1} & 0 & 0 & 0 & 1 \cr
0 & 0 & 0 & 1 & { - 1} \cr
} } \right]$$ is __________.
36
The values of the integrals $$\int\limits_0^1 {\left( {\int\limits_0^1 {{{x - y} \over {{{\left( {x + y} \right)}^3}}}dy} } \right)} dx\,\,$$ and $$\,\,\int\limits_0^1 {\left( {\int\limits_0^1 {{{x - y} \over {{{\left( {x + y} \right)}^3}}}dx} } \right)} dy\,\,$$ are
37
The minimum value of the function $$f\left( x \right) = {1 \over 3}x\left( {{x^2} - 3} \right)\,\,$$ in the interval $$ - 100 \le x \le $$ $$100$$ occurs at $$x=$$ __________.
38
The smaller angle (in degrees) between the planes $$x+y+z=1$$ and $$2x-y+2z=0$$ is ________.
39
$$500$$ students are taking one or more courses out of chemistry, physics and Mathematics. Registration records indicate course enrolment as follows: chemistry $$(329)$$, physics $$(186)$$, Mathematics $$(295)$$, chemistry and physics $$(83)$$, chemistry and Mathematics $$(217)$$, and physic and Mathematics $$(63)$$, How many students are taking all $$3$$ subjects?
40
Passengers try repeatedly to get a seat reservation in any train running between two stations until they are successful. If there is $$40$$% chance of getting reservation in any attempt by a passenger, then the average number of attempts that passengers need to make to get a seat reserved is ___________.
41
The general solution of the differential equation $$\,\,{{{d^2}y} \over {d{x^2}}} + 2{{dy} \over {dx}} - 5y = 0\,\,\,$$ in terms of arbitrary constants $${K_1}$$ and $${K_2}$$ is
42
The residues of a function $$f\left( z \right) = {1 \over {\left( {z - 4} \right){{\left( {z + 1} \right)}^3}}}$$ are
43
An integral $${\rm I}$$ over a counter clock wise circle $$C$$ is given by $${\rm I} = \oint\limits_c {{{{z^2} - 1} \over {{z^2} + 1}}} \,\,{e^z}\,dz$$
If $$C$$ is defined as $$\left| z \right| = 3,$$ then the value of $${\rm I}$$ is
44
In the circuit shown, $$V$$ is a sinusoidal voltage source. The current $$I$$ is in phase with voltage $$V$$. The ratio $${{{\rm{Amplitude of voltage across the capacitor }}} \over {{\rm{Amplitude of voltage across the resistor }}}}$$ is ______.
45
Consider the circuit shown in the figure.
The Thevenin equivalent resistance (in Ω) across P – Q is _________.
46
The switch in the circuit, shown in the figure, was open for a long time and is closed at t = 0.
The current i(t) (in ampere) at t = 0.5 seconds is ________

47
A connection is made consisting of resistance A in series with a parallel combination of
resistances B and C. Three resistors of value
10 Ω, 5 Ω, 2 Ω are provided. Consider all possible
permutations of the given resistors into the positions A, B, C, and identify the configurations
with maximum possible overall resistance, and also the ones with minimum possible overall
resistance. The ratio of maximum to minimum values of the resistances (up to second decimal
place) is ____________.
48
The input x(t) and the output y(t) of a continuous time system are related as
$$y\left( t \right) = \int\limits_{t - T}^t {x\left( u \right)du.} $$. The system is
49
The transfer function of a causal LTI system is H(s) = 1/s. If the input to the system is x(t) = $$\left[ {\sin (t)/\pi t} \right]u(t);$$ where u(t) is a unit step function. The system output y(t) as $$t \to \infty $$ is _____________________.
50
Consider the parallel combination of two LTI systems shown in the figure.
The impulse responses of the systems are
$${h_1}(t) = 2\delta (t + 2)\, - 3\delta (t + 1)$$
$${h_2}(t) = \delta (t - 2)$$
If the input x(t) is a unit step signal, then the energy of y(t) is__________________.
51
Consider an LTI system with magnitude response $$$\left| {H(f)} \right| = \left\{ {\matrix{
{1 - \,{{\left| f \right|} \over {20}},} & {\left| f \right| \le 20} \cr
{0,} & {\left| f \right| > 20} \cr
} } \right.$$$ and phase response Arg[H(f)]= - 2f.
If the input to the system is $$x(t) = 8\cos \left( {20\pi t + \,{\pi \over 4}} \right) + \,16\sin \left( {40\pi t + {\pi \over 8}} \right) + 24\,\cos \left( {80\pi t + {\pi \over {16}}} \right)$$
Then the average power of the output signal y(t) is_____________.
52
An LTI system with unit sample response
$$h\left( n \right) = 5\delta \left[ n \right] - 7\delta \left[ {n - 1} \right] + 7\delta \left[ {n - 3} \right] - 5\delta \left[ {n - 4} \right]$$ is a
53
The signal x(t) = $$\sin \,(14000\,\pi t)$$, where t is in seconds, is sampled at a rate of 9000 samples per second. The sampled signal is the input to an ideal lowpass filter with frequency response H(f) as following: $$H(f) = \left\{ {\matrix{
{1,} & {\left| f \right| \le \,12\,kHz} \cr
{0,} & {\left| f \right| > \,12\,kHz} \cr
} } \right.$$
What is the number of sinusoids in the output and their frequency inkHz?