GATE ECE 2015 Set 1
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GATE ECE

1
In the circuit shown, I1 = 80 mA and I2 b= 4mA. Transistors T1 and T2 are identical. Assume that the thermal voltage VT is 26 mV at 27oC. At 50oC, the value of the voltage V12 = V1 - V2 (in mV) is _______. GATE ECE 2015 Set 1 Analog Circuits - Bipolar Junction Transistor Question 13 English
2
In the circuit shown, assume that the opamp is ideal. The bridge output voltage V0 (in mV) for $$\delta = 0.05$$ is______. GATE ECE 2015 Set 1 Analog Circuits - Operational Amplifier Question 28 English
3
The circuit shown in the figure has an ideal opamp. The oscillation frequency and the condition to sustain the oscillations, respectively, are GATE ECE 2015 Set 1 Analog Circuits - Operational Amplifier Question 27 English
4
A sinusoidal signal of 2 kHz frequency is applied to a delta modulator. The sampling rate and step-size $$\Delta $$ of the delta modulator are 20,000 samples per second and 0.1 V, respectively. To prevent slope overload, the maximum amplitude of the sinusoidal signal (in Volts) is
5
The transmitted signal in a GSM system is of 200 kHz bandwidth and 8 users share a common bandwidth using TDMA. If at a given time 12 users are talking in a cell, the total bandwidth of the signal received by the base station of the cell will be at least (in kHz) ___________________.
6
The input X to the Binary Symmetric Channel (BSC) shown in the figure is ‘1’ with probability 0.8. The cross-over probability is 1/7. If the received bit Y = 0, the conditional probability that ‘1’ was transmitted is _______. GATE ECE 2015 Set 1 Communications - Noise In Digital Communication Question 13 English
7
A source emits bit 0 with probability $${1 \over 3}$$ and bit 1 with probability $${2 \over 3}$$. The emitted bits are communicated to the receiver. The receiver decides for either 0 or 1 based on the received value R. It is given that the conditional density functions of R are as
$${f_{\left. R \right|o}}\,(r) = \left\{ {\matrix{ {{1 \over 4},} & { - \,3\,\, \le \,\,x\,\, \le \,\,1,\,} \cr 0 & {otherwise,} \cr } } \right.and$$
$${f_{R/o}}\,(r) = \left\{ {\matrix{ {{1 \over 6},} & { - \,1\,\, \le \,\,x\,\, \le \,\,5\,,} \cr 0 & {otherwise.} \cr } } \right.$$

The minimum decision error orobability is

8
Consider the signal $$s\left(t\right)\;=\;m\left(t\right)\;\cos\left(2{\mathrm{πf}}_\mathrm c\mathrm t\right)\;+\widehat m\left(t\right)\;\sin\left(2\mathrm\pi\;{\mathrm f}_\mathrm c\mathrm t\right)$$ where $$\widehat m\left(t\right)\;$$ denotes the Hilbert transform of m(t) and the bandwidth of m(t) is very small compared to fc. The signal s(t) is a
9
In the system shown in figure (a), m(t) is a low-pass signal with bandwidth W Hz. The frequency response of the band-pass filter H(f) is shown in figure (b). If it is desired that the output signal z(t) = 10x(t), the maximum value of W (in Hz) should be strictly less than ____________________. GATE ECE 2015 Set 1 Communications - Analog Communication Systems Question 7 English
10
Negative feedback in a closed-loop control system DOES NOT
11
The damping ratio of a series RLC circuit can be expressed as
12
A unity negative feedback system has the open-loop transfer function $$$G\left(s\right)\;=\;\frac K{s\left(s\;+\;1\right)\left(s\;+\;3\right)}$$$ The value of the gain K (>0) at which the root locus crosses the imaginary axis is _________.
13
The open-loop transfer function of a plant in a unity feedback configuration is given as $$G\left(s\right)=\frac{K\left(s+4\right)}{\left(s+8\right)\left(s^2-9\right)}$$.The value of the gain K(>0) for which -1 + j2 lies on the root locus is __________________.
14
A plant transfer function is given as $$$G\left(s\right)=\left(K_p+\frac{K_1}s\right)\left(\frac1{s\left(s+2\right)}\right)$$$ . When the plant operates in a unity feedback configuration, the condition for the stability of the closed loop system is
15
The popular plot of the transfer function G(s)=$${{10\left( {s + 1} \right)} \over {\left( {s + 10} \right)}}$$ for $$0 \le \omega < \infty $$ will be in the
16
A lead compensator network includes a parallel combination of 'R' and 'C' in the feed-forward path. If the transfer function of the compensator is $${G_C}(s) = {{s + 2} \over {s + 4}}.$$ The value of RC is ____
17
Consider a four bit D to A converter. The analog value corresponding to digital signals of values 0000 and 0001 are 0 V and 0.0625 V respectively. The analog value (in Volts ) corresponding to the digitals signal 1111 is ______________.
18
A 16 Kb (=16,384 bit) memory array is designed as a square with an aspect ratio of one (number of rows is equal to the number of columns). The minimum number of address lines needed for the row decoder is _______.
19
The Boolean expression F(X, Y, Z)= $$\overline X Y\overline Z + X\overline {Y\,} \overline Z + XY\overline Z + XYZ$$ converted into the canonical product of sum (POS)from is
20
All the logic gates shown in the figure have a propagation delay of 20 ns. Let A = C = 0 and B = 1 until time t = 0. At t = 0, all the inputs flip (i.e., A = C = 1 and B = 0) and remain in that state. For t > 0, output Z = 1 for a duration (in ns) of ______________. GATE ECE 2015 Set 1 Digital Circuits - Logic Gates Question 9 English
21
A 3-input majority gate is defined by the logic function M (a,b,c) = ab+bc+ca. Which one of the following gates is represented by the function M$$\left( {\overline {M\left( {a,b,c} \right),} M\left( {a,b,\overline c } \right),c} \right)?$$
22
The electric field component of a plane wave traveling in a lossless dielectric medium is given by $$$\overrightarrow E \left( {z,t} \right) = {\widehat a_y}2\cos \left( {{{10}^8}t - {z \over {\sqrt 2 }}} \right)V/m.$$$

The wavelength )in m) for the wave is

23
The electric field intensity of a plane wave traveling in free space is given by the following expression

$$E\left( {x,t} \right) = {\widehat a_{_y}}24\pi \,\,\cos \left( {\omega t - {k_0}x} \right)\,\,\,\left( {V/m} \right)$$. In this field, consider a square area $$10 cm$$ $$ \times $$ $$10 cm$$ on a plane $$x + y = 1$$. The total time-averaged power $$(in mW)$$ passing through the square area is ________.

24
Consider a uniform plane wave with amplitude $$\left( {{E_0}} \right)$$ of $$10\,\,\,V/m$$ and $$1.1 GHz$$ frequency travelling in air, and incident normally on a dielectric medium with complex relative permittivity $$\left( {{\varepsilon _r}} \right)$$ and permeability $$\left( {{\mu _r}} \right)$$ as shown in the figure. GATE ECE 2015 Set 1 Electromagnetics - Uniform Plane Waves Question 21 English

The magnitude of the transmitted electric field component (in V/m) after it has travelled a distance of $$10$$ cm inside the dielectric region is ________.

25
The longitudinal component of the magnetic field inside an air-filled rectangular waveguide made of a perfect electric conductor is given by the following expression $${H_z}(x,\,y,\,z,\,t) = \,0.1\,\cos \,(25\,\,\pi \,x)\,\cos \,(30.3\,\pi y)$$ $$\cos \,(12\,\pi \, \times \,{10^9}\,t\, - \beta \,z)(A/m)$$

The cross-sectional dimemsions of the waveguide are given as a = 0.08 m and b = 0.033 m. The mode of propagation inside the waveguide is

26
The built-in potential of an abrupt p-n junction is 0.75V. If its junction capacitance (CJ) at a reverse bias (VR) of 1.25V is 5pF, the value of CJ (in pF) when VR = 7.25V is ___________.
27
A silicon sample is uniformly doped with donor type impurities with a concentration of $$10^{16}/cm^3$$.The electron and hole mobilities in the sample are $$1200\;cm^2/V-s$$ and $$400\;cm^2/V-s$$ respectively. Assume complete ionization of impurities. The charge of an electron is $$1.6\;\times\;10^{-19}\;C$$.The resistivity of the sample $$\left(in\;\Omega-cm\right)$$ is _____________.
28
A region of negative differential resistance is observed in the current voltage characteristics of a silicon PN junction if
29
In the circuit shown below, the Zener diode is ideal and the Zener voltage is 6V. The output voltage V0 (in volts) is ________. GATE ECE 2015 Set 1 Electronic Devices and VLSI - PN Junction Question 21 English
30
A MOSFET in saturation has a drain current of 1 mA for VDS =0.5V. If the channel length modulation coefficient is 0.05 V-1, the output resistance (in k$$\Omega $$) of the MOSFET is______
31
For the NMOSFET in the circuit shown, in the threshold voltage is Vth, where Vth>0. The source voltage Vss is varied from 0 to VDD. Neglecting the channel length modulation, the drain current ID as a function of Vss is represented by GATE ECE 2015 Set 1 Electronic Devices and VLSI - IC Basics and MOSFET Question 15 English
32
Consider system of linear equations : $$$x-2y+3z=-1$$$ $$$x-3y+4z=1$$$ and $$$-2x+4y-6z=k,$$$

The value of $$'k'$$ for which the system has infinitely many solutions is _______.

33
The value of $$'P'$$ such that the vector $$\left[ {\matrix{ 1 \cr 2 \cr 3 \cr } } \right]$$ is an eigenvector of the matrix $$\left[ {\matrix{ 4 & 1 & 2 \cr P & 2 & 1 \cr {14} & { - 4} & {10} \cr } } \right]$$ is ________.
34
A function $$f\left( x \right) = 1 - {x^2} + {x^3}\,\,$$ is defined in the closed interval $$\left[ { - 1,1} \right].$$ The value of $$x,$$ in the open interval $$(-1,1)$$ for which the mean value theorem is satisfied, is
35
The maximum area (in square units) of a rectangle whose vertices lie on the ellipse $${x^2} + 4{y^2} = 1\,\,$$ is
36
Which one of the following graphs describes the function? $$f\left( x \right) = {e^{ - x}}\left( {{x^2} + x + 1} \right)\,?$$
37
A vector $$\overrightarrow P $$ is given by $$\,\,\overrightarrow P = {x^3}y\overrightarrow a {}_x - {x^2}{y^2}\overrightarrow a {}_y - {x^2}yz\overrightarrow a {}_z.\,\,\,$$ Which one of the following statements is TRUE?
38
Suppose $$A$$ & $$B$$ are two independent events with probabilities $$P\left( A \right) \ne 0$$ and $$P\left( B \right) \ne 0.$$ Let $$\overrightarrow A $$ & $$\overrightarrow B $$ be their complements. Which of the following statements is FALSE?
39
The input $$X$$ to the Binary Symmetric Channel (BSC) shown in the figure is $$'1'$$ with probability $$0.8.$$ The cross-over probability is $$1/7$$. If the received bit $$Y=0,$$ the conditional probability that $$'1'$$ was transmitted is _______. GATE ECE 2015 Set 1 Engineering Mathematics - Probability and Statistics Question 15 English
40
The Solution of the differential equation $$\,{{{d^2}y} \over {d{t^2}}} + 2{{dy} \over {dt}} + y = 0\,\,$$ with $$\,y\left( 0 \right) = {y^1}\left( 0 \right) = 1\,\,$$ is
41
Let $$z=x+iy$$ be a complex variable. Consider that contour integration is performed along the unit circle in anticlockwise direction . Which one of the following statement is NOT TRUE?
42
In an 8085 microprocessor, the shift registers which store the result of an addition and the overflew bit are, respectively.
43
The damping ratio of a series $$RLC$$ circuit can be expressed as
44

In the network shown in the figure, all resistors are identical with R = 300 $$\Omega$$. The resistance Rab (in $$\Omega$$) of the network is _______.

GATE ECE 2015 Set 1 Network Theory - Network Theorems Question 38 English
45
In the circuit shown, the switch SW is thrown from position A to position B at time t = 0. The energy (in $$\mu J$$) taken from the 3V source to charge the 0.1$$\mu$$F capacitor from 0V to 3V is GATE ECE 2015 Set 1 Network Theory - Transient Response Question 41 English
46
In the circuit shown, at resonance, the amplitude of the sinusoidal voltage (in Volts) across the capacitor is ___________.

GATE ECE 2015 Set 1 Network Theory - Sinusoidal Steady State Response Question 61 English
47
In the given circuit, the maximum power (in Watts) that can be transferred to the load RL is ___________________. GATE ECE 2015 Set 1 Network Theory - Sinusoidal Steady State Response Question 50 English
48

In the given circuit, the values of V1 and V2 respectively are

GATE ECE 2015 Set 1 Network Theory - Network Elements Question 28 English
49
In the circuit shown, switch SW is closed at t = 0. Assuming zero initial conditions, the value of vc(t) (in Volts) at t= 1 sec is ___________. GATE ECE 2015 Set 1 Network Theory - Transient Response Question 18 English
50
The solution of the differential equation $${{h\left( {t + 1} \right)} \over {h\left( t \right)}}\,\,\,\,\,{{{d^2}y} \over {d{t^{ \to 2}}}} + {{2\,dy} \over {dt}} + y\, = \,0$$ with $$\,y\left( 0 \right)\, = \,y'\left( 0 \right)\, = \,1$$ is
51
Two sequences [a, b, c ] and [A, B, C ] are related as,
$$\left[ {\matrix{ A \cr B \cr C \cr } } \right] = \left[ {\matrix{ 1 \cr 1 \cr 1 \cr } {\mkern 1mu} \,\matrix{ 1 \cr {W_3^{ - 1}} \cr {W_3^{ - 2}} \cr } \,\matrix{ 1 \cr {W_3^{ - 2}} \cr {W_3^{ - 4}} \cr } } \right]{\mkern 1mu} \left[ {\matrix{ a \cr b \cr c \cr } } \right]$$ Where
$${W_3}$$ = $${e^{j{{2\pi } \over 3}}}$$ .
if another sequence $$\left[ {p,\,q,\,r} \right]$$ is derived as,
$$\left[ {\matrix{ p \cr q \cr r \cr } } \right] = \left[ {\matrix{ 1 \cr 1 \cr 1 \cr } \,\,\matrix{ 1 \cr {W_3^1} \cr {W_3^2} \cr } \,\matrix{ 1 \cr {W_3^2} \cr {W_3^4} \cr } } \right]\,\left[ {\matrix{ 1 \cr 0 \cr 0 \cr } \,\matrix{ 0 \cr {W_3^2} \cr {0\,} \cr } \,\matrix{ 0 \cr 0 \cr {W_3^4} \cr } } \right]\,\left[ {\matrix{ {A/3} \cr {B/3} \cr {C/3} \cr } } \right]$$ ,
Then the relationship between the sequences $$\left[ {p,\,q,\,r} \right]$$ and $$\left[ {a,\,b,\,c} \right]$$ is
52
Consider two real sequences with time- origin marked by the bold value, $${x_1}\left[ n \right] = \left\{ {1,\,2,\,3,\,0} \right\}\,,\,{x_2}\left[ n \right] = \left\{ {1,\,3,\,2,\,1} \right\}$$ Let $${X_1}(k)$$ and $${X_2}(k)$$ be 4-point DFTs of $${x_1}\left[ n \right]$$ and $${x_2}\left[ n \right]$$, respectively. Another sequence $${X_3}(n)$$ is derived by taking 4-ponit inverse DFT of $${X_3}(k)$$= $${X_1}(k)$$$${X_2}(k)$$. The value of $${x_3}\left[ 2 \right]$$
53
The pole-zero diagram of a causal and stable discrete-time system is shown in the figure. The zero at the origin has multiplicity 4. The impulse response of the system is ℎ[n]. If ℎ[0] =1, we can conclude. GATE ECE 2015 Set 1 Signals and Systems - Discrete Time Signal Z Transform Question 20 English
54
For the discrete-time system shown in the figure, the poles of the system transfer function are located at GATE ECE 2015 Set 1 Signals and Systems - Discrete Time Signal Z Transform Question 19 English
55
The result of the convolution $$x\left( { - t} \right) * \delta \left( { - t - {t_0}} \right)$$ is
56
In the system shown in Figure (a), m(t) is a low-pass signal with bandwidth W Hz. The frequency response of the band-pass filter H(f) is shown in Figure (b). If it is desired that the output signal z(t) = 10x(t), the maximum value of W (in Hz) should be strictly less than ___________________________ GATE ECE 2015 Set 1 Signals and Systems - Transmission of Signal Through Continuous Time LTI Systems Question 11 English
57
The waveform of a periodic signal x(t) is shown in the figure. GATE ECE 2015 Set 1 Signals and Systems - Miscellaneous Question 15 English

A signal g(t) is defined by $$g(t) = x\left( {{{t - 1} \over 2}} \right)$$.

The average power of g(t) is___________________________.

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