Electronics and Communication Gate 2016 Set-1 Questions with Answer

Ques 27 GATE 2016 SET-1

Consider the oscillator circuit shown in the figure. The function of the network (shown in dotted lines) consisting of the 100Ω resistor in series with the two diodes connected back-to-back is to:

introduce amplitude stabilization by preventing the op amp from saturating and thus producing sinusoidal oscillations of fixed amplitude

introduce amplitude stabilization by forcing the opamp to swing between positive and negative saturation and thus producing square wave oscillations of fixed amplitude

introduce frequency stabilization by forcing the circuit to oscillate at a single frequency

enable the loop gain to take on a value that produces square wave oscillations

(a) is the correct answer.

Ques 28 GATE 2016 SET-1

An ideal opamp has voltage sources V₁,V₃,V₅,...,V_N-1 connected to the non-inverting input and V₂, V₄,V₆,...,V_N connected to the inverting input as shown in the figure below (+V_CC=15 volt, -V_cc=-15 volt). The voltages V1, V2, V3, V4, V₅, V₆... are 1, -1/2, 1/3, -1/4, 1/5, -1/6, ... volt, respectively. As N approaches infinity, the output voltage (in volt) is

(15.25) is the correct answer.

Ques 29 GATE 2016 SET-1

A small percentage of impurity is added to an intrinsic semiconductor at 300 K.

Which one of the following statements is true for the energy band diagram shown in the following figure?

Intrinsic semiconductor doped with pentavalent atoms to form n-type semiconductor

Intrinsic semiconductor doped with trivalent atoms to form n-type semiconductor

Intrinsic semiconductor doped with pentavalent atoms to form p-type semiconductor

Intrinsic semiconductor doped with trivalent atoms to form p-type semiconductor

(a) is the correct answer.

Ques 30 GATE 2016 SET-1

Consider the following statements for a metal oxide semiconductor field effect transistor (MOSFET):
P: As channel length reduces, OFF-state current increases.
Q: As channel length reduces, output resistance increases.
R: As channel length reduces, threshold voltage remains constant.
S: As channel length reduces, ON current increases.
Which of the above statements are INCORRECT?

P and Q

P and S

Q and R

R and S

Ques 31 GATE 2016 SET-1

Consider a silicon p-n junction with a uniform acceptor doping concentration of 10¹⁷cm^-3 on the p-side and a uniform donor doping concentration of 10¹⁶cm^-3 on the n-side. No external voltage is applied to the diode. Given: kT/q=26mV, n_i=1.5×10¹⁰cm^-3, ε_Si=12ε₀, ε₀=8.85×10^-14F/m and q=1.6×10^-19C. The charge per unit junction area (nC cm^-2) in the depletion region on the p-side is

(-4.8) is the correct answer.

Ques 32 GATE 2016 SET-1

Consider an n-channel metal oxide semiconductor field effect transistor (MOSFET) with a gate-to-source voltage of 1.8 V. Assume that μ_NC_ox(W/L)=4, the threshold voltage is 0.3V, and the channel length modulation parameter is 0.09 V^-1. In the saturation region, the drain conductance (in micro seimens) is

(28.35) is the correct answer.

Ques 33 GATE 2016 SET-1

The figure below shows the doping distribution in a p-type semiconductor in log scale.

The magnitude of the electric field (in kV/cm) in the semiconductor due to non uniform doping is

(1.18) is the correct answer.

Ques 34 GATE 2016 SET-1

Consider a silicon sample at T=300 K with a uniform donor density N_d=5×10¹⁶cm^-3, illuminated uniformly such that the optical generation rate is G_opt=1.5×10²⁰cm^-3s^-1 throughout the sample. The incident radiation is turned off at t=0. Assume low-level injection to be valid and ignore surface effects. The carrier lifetimes are τ_p0=0.1 μs and τ_n0=0.5 μs.

The hole concentration at t=0 and the hole concentration at t=0.3 μs, respectively, are

1.5×10¹³cm^-3 and 7.47×10¹¹cm^-3

1.5×10¹³cm^-3 and 8.23×10¹¹cm^-3

7.5×10¹³cm^-3 and 3.73×10¹¹cm^-3

7.5×10¹³cm^-3 and 4.12×10¹¹cm^-3

(a) is the correct answer.

Ques 35 GATE 2016 SET-1

A p-i-n photodiode of responsivity 0.8A/W is connected to the inverting input of an ideal opamp as shown in the figure, V_CC=15V, -V_CC=-15V. Load resistor R_L=10 kΩ. If 10 μW of optical power is incident on the photodiode, then the value of the photocurrent (in μA) through the load is

(8) is the correct answer.

Ques 36 GATE 2016 SET-1

Let M⁴=I (where I denotes the identity matrix) and M≠I, M≠M² and M≠M³. Then, for any natural number k, M^-1 equals:

M^4k+1

M^4k+2

M^4k+3

M^4k

Ques 37 GATE 2016 SET-1

Given the following statements about a function f:R→R, select the right option:
P: If f(x) is continuous at x=x₀, then it is also differentiable at x=x₀.
Q: If f(x) is continuous at x=x₀, then it may not be differentiable at x=x₀
R: If f(x) is differentiable at x=x₀, then it is also continuous at x=x₀.