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ISROElectronics & Communication Engineering 2020
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80
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180 mins
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ESE & GATE EC - Previous Year Papers
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PYP
ISROElectronics & Communication Engineering 2020
The plane wave propagating through the dielectric has the magnetic field component as H = 20e-ax cos(ωt – 0.25x) ay A/m (ax, ay, az are unit vectors along x, y and z axis respectively).
Determine the polarization of the wave
Determine the polarization of the wave
PYP
ISROElectronics & Communication Engineering 2020
In free space, H = 0.1 cos(ωt – βx) az A/m (ax, ay, az are unit vectors along x, y and z axis respectively). The total power passing through a square plate of side 10 cm on plane x + 2y = 1.0, is approximately:
PYP
ISROElectronics & Communication Engineering 2020
Consider the rectangular cavity as shown below:
If a = c > b, the dominant mode of resonance corresponding to the above rectangular cavity is
If a = c > b, the dominant mode of resonance corresponding to the above rectangular cavity is
PYP
ISROElectronics & Communication Engineering 2020
A video camera generates data at a rate of 5 Mbps. The data is channel coded at rate 1/3 and 8 PSK modulated. Which of the following statements is correct?
PYP
ISROElectronics & Communication Engineering 2020
Evaluate where,
PYP
ISROElectronics & Communication Engineering 2020
Consider a transformation where R3 and R2 represent three and two dimensional real column vectors respectively. Also, T(x) = Ax for some matrix A and for each x in R3. How many rows and columns does A have and what is the its maximum possible rank?
PYP
ISROElectronics & Communication Engineering 2020
The output of a three element co-linear antenna array operating in a free space environment is combined (after appropriate phase shifting) to maximize the signal received from a particular direction as shown in figure.
If the inter-element spacing is half of the signal wavelength and direction of maximum response is 30° from the perpendicular to the array, what are the phases to be applied to each element? Consider the first element as the reference.
If the inter-element spacing is half of the signal wavelength and direction of maximum response is 30° from the perpendicular to the array, what are the phases to be applied to each element? Consider the first element as the reference.
PYP
ISROElectronics & Communication Engineering 2020
The transmission line of characteristic impedance 50 Ω and feeding a purely resistive load of 200 Ω uses single quarter wavelength long short-circuit stub which is placed at a distance d from the load. The VSWR on the transmission line section of length d and VSWR on the stub respectively are
PYP
ISROElectronics & Communication Engineering 2020
The plane Y = 0 carries a uniform current density of –20mA/m. The magnetic field intensity at X = 1, Y = 10 and Z = –2 is
PYP
ISROElectronics & Communication Engineering 2020
A charge of 2 Coulombs is placed near a grounded conducting plate at a distance of 1 m. The force acting between the charge of 2 C and ground conducting plate in Newton is
PYP
ISROElectronics & Communication Engineering 2020
A data sequence x[n] = {1, 2, 3, 4, 5} passes through a linear time-invariant system with impulse response h[n] = {5, 4, 3, 2, 1}. The output of the filter will be
PYP
ISROElectronics & Communication Engineering 2020
Consider a signal v(t) with Fourier transform V(f). If V′(f) represents the Fourier transform of v(2t), what is the relation of V′(f) to V(f)?
PYP
ISROElectronics & Communication Engineering 2020
If one of the code words of a Hamming (7, 4) code is 0001011, which of the following cannot be the valid code word in the same group?
PYP
ISROElectronics & Communication Engineering 2020
Which of the following digital modulations can be decoded non-coherently?
PYP
ISROElectronics & Communication Engineering 2020
A mobile antenna receives two copies of the signal transmitted by the base station. The first copy is the line-of-sight component and the other is a reflected component which is 20 dB weaker in terms of Power than the LoS component and delayed by 100 ns. If the signal is sufficiently wideband, causing constructive and destructive interference at different frequency points within the signal bandwidth. What will be the ratio of maximum to minimum signal level variation across bandwidth and what will be the frequency separation between two consecutive maxima or minima?
PYP
ISROElectronics & Communication Engineering 2020
An antenna with an efficiency of 90% has a maximum radiation intensity of 0.,5 W/Steradian. Calculate the directive gain of the antenna when the input power to the antenna when the input power to the antenna is 0.4 W
PYP
ISROElectronics & Communication Engineering 2020
In a semiconductor device, if Fermi level (EF) is positioned at conduction band (EC). Determine the approximate probability of finding electrons in states at (EC + kT) (where k is Boltzmann constant and T is device temperature in Kelvin).
PYP
ISROElectronics & Communication Engineering 2020
For the following energy band diagram, determine the approximate resistivity for x > L portion of semiconductor. Eg = 1.12 eV, T = 300 K, µn = 600 cm2/V-sec, µp = 400 cm2/V-sec, ni = 1010/cm3.
PYP
ISROElectronics & Communication Engineering 2020
The radiation intensity of a given antenna is U = 2(sinθ sinφ) in the range 0 ≤ θ ≤ π and 0 ≤ φ ≤ π and 0 elsewhere. The direction is
PYP
ISROElectronics & Communication Engineering 2020
Which of the following is an example of oversampling ADC architecture?
PYP
ISROElectronics & Communication Engineering 2020
A radar receiver has a detection SNR threshold of 10 dB for a 4 MHz bandwidth signal at 300 MHz frequency. If the transmit EIRP of the radar is 40 dBW and receive G/T is 10 dB/K, what is the maximum Radar cross-section (in dB-meter square) detectable at 10 km range? (Given: 10 log(4π) = 11, 10 log(k) = –228.6, k is Boltzmann constant).
PYP
ISROElectronics & Communication Engineering 2020
A source generates four messages m1, m2, m3 and m4 with probabilities 0.5, 0.25, 0.125 and 0.125 respectively. The messages are generated independently of each other. A source coder assigns binary code to each message. Which of the following codes has minimum average length is also uniquely decodable (sequence as per m1, m2, m3, m4)?
PYP
ISROElectronics & Communication Engineering 2020
For the given circuit, switch remains closed for a long time and opens at t = 0 seconds. Assuming ideal model for every device, find steady state magnitude of voltage at capacitor.
PYP
ISROElectronics & Communication Engineering 2020
For the given circuit, aspect ratio of M1 transistor is 20/0.5, ID1 = 200 µA, VTHO = 0.6 V, 2φF = 0.81 V, γ = 0.4 V2 and µnCox = 59.5 mA/V2. If Vin = 1.2 V, find the minimum value of aspect ratio of M2 transistor to remain saturated. ( = 3.16)
PYP
ISROElectronics & Communication Engineering 2020
Two coherent microwave power sources of same frequency f, each generating P Watts of average power, are combined using a four port network in the following manner:
If the S-parameter of 4-port network are , what should be the phase difference between the inputs to maximize the output at port 2 and what is the maximum power?
If the S-parameter of 4-port network are , what should be the phase difference between the inputs to maximize the output at port 2 and what is the maximum power?
PYP
ISROElectronics & Communication Engineering 2020
Which of the following statement is wrong?
PYP
ISROElectronics & Communication Engineering 2020
Which of the following statement is correct?
PYP
ISROElectronics & Communication Engineering 2020
Which one plot gives the closed resemblance to the stability S(ICO) of emitter bias configuration of BJT with respect to RE/RB = ? (RE is emitter resistance and RB is base resistance).
PYP
ISROElectronics & Communication Engineering 2020
For the given amplifier circuit, find the input cut-off frequency. FET parameters are gm = 4 mA/V, Cgs = 4 pf, rds = 40 kΩ, Cgd = 2 pF
PYP
ISROElectronics & Communication Engineering 2020
Which of the following digital devices requires an external refresh circuit?
PYP
ISROElectronics & Communication Engineering 2020
What would be the maximum operating frequency of Mod-8 counter constructed with JK flip flops, having propagation delay of 8 ns?
PYP
ISROElectronics & Communication Engineering 2020
The following state diagram represents which of the input equation. (Given DA = [A, x, y]) (Where DA denotes a D FF with output. The x and y are the inputs to the circuit)
PYP
ISROElectronics & Communication Engineering 2020
Which of the following logic circuits do not have no-change condition?
PYP
ISROElectronics & Communication Engineering 2020
n VHDL, following statement is written a process, where Clock frequency is 24 MHz.
If (clock’ event and clock = ‘1’) then
counter_4bit <= counter_4bit + x “1”;
End if;
The frequency of counter_4bit (2) will be:
If (clock’ event and clock = ‘1’) then
counter_4bit <= counter_4bit + x “1”;
End if;
The frequency of counter_4bit (2) will be:
PYP
ISROElectronics & Communication Engineering 2020
Initial voltage of C1 capacitance is 3 V in the given circuit. Correct sketch of Vx as a function of time is. (Threshold voltage (Vth) = 0.5 V).
PYP
ISROElectronics & Communication Engineering 2020
An SRAM has address lines from A0 to A19 and data width from D0 to D15. Total capacity of the SRAM will be
PYP
ISROElectronics & Communication Engineering 2020
Which of the following digital integrated circuit cannot be used as wired logic connections?
PYP
ISROElectronics & Communication Engineering 2020
The logic function implemented by following circuit can be represented as
PYP
ISROElectronics & Communication Engineering 2020
The value of C required for sinusoidal oscillation of frequency = 2 kHz in the given circuit is
PYP
ISROElectronics & Communication Engineering 2020
In the given circuit, Vbe = 0.7 V, Vz = 5.3 V, β = 100. V0 is
PYP
ISROElectronics & Communication Engineering 2020
A 18 µF capacitor holding charge of Q coulomb is connected to the circuit at time t = 0 sec.
The time at which the capacitor will be discharged to approximately Q/2.72 coulombs.
The time at which the capacitor will be discharged to approximately Q/2.72 coulombs.
PYP
ISROElectronics & Communication Engineering 2020
Determine the value of voltage V1 in the figure shown below.
The value of voltage V1 in volts is
The value of voltage V1 in volts is
PYP
ISROElectronics & Communication Engineering 2020
Output characteristics of a BJT amplifier is given. Find the minimum collector current required for r0 = 50 kΩ. (r0 is output resistance).
PYP
ISROElectronics & Communication Engineering 2020
In the given circuits, S1 switch remains closed and S2 remains open for the long time. At t = 0, S1 opens and S2 closes and remain in this position for the long time. Find drain current for t < 0 and t >> 0 respectively if, µn Cox = 100 µA/V2 and Aspect ratio = 2.
PYP
ISROElectronics & Communication Engineering 2020
In the circuit shown below, switch S1 is closed at t = 0 seconds. Switch S2 is opened at t = 0 seconds.
The current flowing through the inductor of 0.3 H at t = 8 mili seconds is
The current flowing through the inductor of 0.3 H at t = 8 mili seconds is
PYP
ISROElectronics & Communication Engineering 2020
The transmission parameters of the network given below is represented in the matrix form as
Calculate the Transmission parameter B of [T] matrix.
Calculate the Transmission parameter B of [T] matrix.
PYP
ISROElectronics & Communication Engineering 2020
In the circuit shown diodes are ideal. Which is the correct representation of transfer characteristics of the circuit?
PYP
ISROElectronics & Communication Engineering 2020
Consider the R-L-C network shown below,
The average power absorbed by the inductor in Watts is
The average power absorbed by the inductor in Watts is
PYP
ISROElectronics & Communication Engineering 2020
The total number of possible trees corresponding to the network shown below is
PYP
ISROElectronics & Communication Engineering 2020
For an n-type Ge specimen, width = 4 mm, length = 1 mm, current (along the length of specimen) = 1 mA, magnetic field (perpendicular to the current flow direction) = 0.1 Wb/m2 and Hall voltage magnitude = 0.005 V. Calculate the majority carriers density.
PYP
ISROElectronics & Communication Engineering 2020
The following table gives the forward characteristics of a Si diode. Estimate the temperature of a diode junction. (Given: ln(0.2) = –1.609)
PYP
ISROElectronics & Communication Engineering 2020
An n-channel MOS transistor is made on a p-type substrate with Na = 1015 cm–3. Find approximate depletion charge per unit area (Qd) at strong inversion.
PYP
ISROElectronics & Communication Engineering 2020
For a p-channel Si JFET, Na = 3 × 1016 cm–3, Nd = 1018 cm–3. Channel thickness dimension is a = 0.33 µm. Find approximate pinch-off voltage Vp. {ni = 1010 cm–3, VT = 26 mV, ln(3) = 1.098}.
PYP
ISROElectronics & Communication Engineering 2020
Consider the circuit shown below:
The power factor of the above circuit as seen by the source is
The power factor of the above circuit as seen by the source is
PYP
ISROElectronics & Communication Engineering 2020
All the three inductors are perfectly coupled as shown below, the value of total inductance (in Henry) across the terminal AB is
PYP
ISROElectronics & Communication Engineering 2020
For a uniformly doped npn transistor, find the approximate emitter injection efficiency. Given that:
NE = 2 × 1018 cm–3, NB = 1017 cm–3, NC = 4 × 1019 cm–3, DE = 8 cm2/s, DC = 28 cm2/s, DB = 20 cm2/s, xE = 0.5 µm, xB = 0.3 µm.
NE = 2 × 1018 cm–3, NB = 1017 cm–3, NC = 4 × 1019 cm–3, DE = 8 cm2/s, DC = 28 cm2/s, DB = 20 cm2/s, xE = 0.5 µm, xB = 0.3 µm.
PYP
ISROElectronics & Communication Engineering 2020
In a long p-type Si-bar with cross-sectional area = 0.5 cm2 and Na = 2 × 1017 cm–3, extra holes = 1016 cm–3 are injected. Assume µp = 500 cm2/Vs, ni = 1010 cm–3 and τp = 10–10 s, find minority carrier lifetime.
PYP
ISROElectronics & Communication Engineering 2020
In a p-type Si at 300 K and Na = 8 × 1015 cm–3, variation of space-charge density in the semiconductor as a function of surface potential is plotted, then select the true statement for weak inversion region. Given that ps and ns are hole and electron concentrations at the surface.
PYP
ISROElectronics & Communication Engineering 2020
In order to ensure that the output voltage of an op-amp is zero, when both its inputs are grounded
PYP
ISROElectronics & Communication Engineering 2020
Consider the resistive network shown below, the value of Norton current across the terminal AB
PYP
ISROElectronics & Communication Engineering 2020
The transfer characteristic of the different types of MOSFETs is shown below, where ID is drain current and VGS is the Gate-Source voltage, the correct combination of MOSFET w.r.t. to transfer characteristics is
Type of MOSFET
(P) P-Channel Enhancement MOSFET
(Q) P-Channel Depletion MOSFET
(R) N-Channel Enhancement MOSFET
(S) N-Channel Depletion MOSFET
Transfer Characteristics
Type of MOSFET
(P) P-Channel Enhancement MOSFET
(Q) P-Channel Depletion MOSFET
(R) N-Channel Enhancement MOSFET
(S) N-Channel Depletion MOSFET
Transfer Characteristics
PYP
ISROElectronics & Communication Engineering 2020
Acceptor impurity concentration of Si at 300K is 1019 cm–3. Calculate the concentration of donor impurity atoms that must be added so that Si is n-type and the Fermi Energy is 26 meV below the conduction band edge.
(Given: Effective density state NC = 2.7 × 1019 cm–3 and Thermal Voltage (VT ) at 300K is 26 mV)
(Given: Effective density state NC = 2.7 × 1019 cm–3 and Thermal Voltage (VT ) at 300K is 26 mV)
PYP
ISROElectronics & Communication Engineering 2020
The electric field between two parallel plates placed in vacuum is ‘E’. If a slab of dielectric constant is inserted in between the plates such that the normal to the boundary makes an angle 45° with the lines of electric force in between the plates. Find the angle (θ) between the electric lines in the medium between the plates (vacuum) and dielectric slab.
PYP
ISROElectronics & Communication Engineering 2020
Two parallel perfectly conducting planes of infinite extent are placed ‘b’ distance apart so that the cut-off frequency of the lowest order TE mode is 15 GHz. If additionally, two perfectly conducting planes are placed 10 mm apart so as to form a rectangular waveguide as shown in figure. Find the cut-off frequency of TE11 mode.
PYP
ISROElectronics & Communication Engineering 2020
Consider the AND logic circuit in which V2 = 3 V and V1 lies between 0 to 5 volts. The output voltage is V0. The cut-in voltage of the diode D1 and D2 is 0.6 Volts. The output voltage V0 versus V1 corresponding to the below network is
PYP
ISROElectronics & Communication Engineering 2020
Following are the applications of a Buck and Boost Converters respectively
A. Regulated DC power supplies
B. Regenerative braking of DC motors
C. DC motor speed control
A. Regulated DC power supplies
B. Regenerative braking of DC motors
C. DC motor speed control
PYP
ISROElectronics & Communication Engineering 2020
In a MOSFET, SiO2 breaks down at electric field of the order of 5 × 106 V/cm. For a gate oxide of thickness 1000 Å and channel thickness of 2 µm, what is the maximum VGS it can withstand?
PYP
ISROElectronics & Communication Engineering 2020
Which of the following is false for a Thyristor?
A- Thyristor is a majority-carrier device.
B- The forward-bias portion of Thyristor’s i-v characteristics has two stable operating regions.
C- The forward-bias portion of Thyristor’s i-v characteristic has one stable operating region.
D- The negative gate current turns off the Thyristor.
A- Thyristor is a majority-carrier device.
B- The forward-bias portion of Thyristor’s i-v characteristics has two stable operating regions.
C- The forward-bias portion of Thyristor’s i-v characteristic has one stable operating region.
D- The negative gate current turns off the Thyristor.
PYP
ISROElectronics & Communication Engineering 2020
The Zener regulator circuit shown below consists of Si based Zener diode and Ge diode. The cut-in Voltage of Ge diode is 0.2 Volts, whereas cut-in Voltage of Si-diode is 0.7 Volts.
The output voltage (Vo) of the Zener regulator circuit is
The output voltage (Vo) of the Zener regulator circuit is
PYP
ISROElectronics & Communication Engineering 2020
The asymptotic bode plot for the gain magnitude of a minimum phase system G(s) is shown in figure below.
The steady state error for the ramp input is_______
The steady state error for the ramp input is_______
PYP
ISROElectronics & Communication Engineering 2020
Identify the convertor topologies from the figures given below:
PYP
ISROElectronics & Communication Engineering 2020
Consider two control systems with following transfer function,
System 1 : System 2 : Which of the following is true?
System 1 : System 2 : Which of the following is true?
PYP
ISROElectronics & Communication Engineering 2020
A system’s open loop transfer function is given If system is having a unity negative feedback, which of the following is true for such system to be stable?
PYP
ISROElectronics & Communication Engineering 2020
The third peak overshoot and second undershoot of the step response of the second order underdamped system is given by
PYP
ISROElectronics & Communication Engineering 2020
Consider the Nyquist plot of the second order underdamped system shown in the below figure.
The Resonant Frequency corresponding to the Nyquist plot is
The Resonant Frequency corresponding to the Nyquist plot is
PYP
ISROElectronics & Communication Engineering 2020
The unit step response of a system with the transfer function is given by which of the following? (A unit step function is represented by u(t)).
PYP
ISROElectronics & Communication Engineering 2020
The system is to be compensated such that its gain-crossover frequency becomes same as its uncompensated Phase-crossover frequency. Which of the following is the phase crossover frequency of the compensated system?
PYP
ISROElectronics & Communication Engineering 2020
A discrete time, linear time invariant system with input sequence xn and output sequence yn is characterised by
yn = 0.1xn + 0.9 yn – 1
If two such systems are connected in series, which of the following is the governing difference equation of the overall system?
yn = 0.1xn + 0.9 yn – 1
If two such systems are connected in series, which of the following is the governing difference equation of the overall system?
PYP
ISROElectronics & Communication Engineering 2020
The total number of feedback loops of the signal flow graph is, where R is input and C is output.
PYP
ISROElectronics & Communication Engineering 2020
From the below given Nyquist plot, calculate the number of open loop poles on the right hand side of s-plane for the closed loop system to be stable.
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