Electronics and Communication Gate 2015 Set-3 Questions with Answer

Ques 1 GATE 2015 SET-3

In the circuit shown in the figure, the BJT has a current gain (β) of 50. For an emitter-base voltage V_EB = 600 mV, the emitter-collector voltage V_EC (in Volts) is __________.

(2) is the correct answer.

Ques 2 GATE 2015 SET-3

In the circuit shown using an ideal opamp, the 3-dB cut-off frequency (in Hz) is __________.

(159) is the correct answer.

Ques 3 GATE 2015 SET-3

In the circuit shown, assume that diodes D₁ and D₂ are ideal. In the steady state condition, the average voltage V_ab (in Volts) across the 0.5 μF capacitor is __________.

(100) is the correct answer.

Ques 4 GATE 2015 SET-3

In the circuit shown, assume that the opamp is ideal. If the gain (v₀/v_in) is -12, the value of R (in kΩ) is __________.

(1) is the correct answer.

Ques 5 GATE 2015 SET-3

In the circuit shown, both the enhancement mode NMOS transistors have the following characteristics: k_n = μ_n C_ox(W/L) = 1 mA/V²; V_TN = 1V. Assume that the channel length modulation parameter λ is zero and body is shorted to source. The minimum supply voltage V_DD (in volts) needed to ensure that transistor M₁ operates in saturation mode of operation is __________.

(3) is the correct answer.

Ques 6 GATE 2015 SET-3

In the circuit shown, assume that the diodes D₁ and D₂ are ideal. The average value of voltage V_ab (in Volts), across terminals 'a' and 'b' is __________.

(5) is the correct answer.

Ques 7 GATE 2015 SET-3

The modulation scheme commonly used for transmission from GSM mobile terminals is

4-QAM

16-PSK

Walsh-Hadamard orthogonal codes

Gaussian Minimum Shift Keying (GMSK)

(d) is the correct answer.

Ques 8 GATE 2015 SET-3

A message signal m(t) = A_msin(2π f_m t) is used to modulate the phase of a carrier A_ccos(2π f_c t) to get the modulated signal y(t) = A_ccos(2π f_c t + m(t)). The bandwidth of y(t)

depends on A_m but not on f_m

depends on f_m but not on A_m

depends on both A_m and f_m

does not depend on A_m or f_m

Ques 9 GATE 2015 SET-3

The complex envelope of the bandpass signal x(t) = -√2[sin(π t/5)/(π t/5)]sin(π t - π/4), centered about f = 1/2 Hz, is

[sin(π t/5)/(π t/5)]e^jπ/4

[sin(π t/5)/(π t/5)]e^-jπ/4

√2[sin(π t/5)/(π t/5)]e^jπ/4

√2[sin(π t/5)/(π t/5)]e^-jπ/4

(d) is the correct answer.

Ques 10 GATE 2015 SET-3

A random binary wave y(t) is given by y(t) = ∑_n=-∞^∞ X_n p(t-nT-φ) where p(t) = u(t) - u(t-T), u(t) is the unit step function and φ is an independent random variable with uniform distribution in [0,T]. The sequence {X_n} consists of independent and identically distributed binary valued random variables with P{X_n=+1} = P{X_n=-1}=0.5 for each n. The value of the autocorrelation R_yy(3T/4) ≜ E[y(t)y(t-3T/4)] equals __________.

(0.25) is the correct answer.

Ques 11 GATE 2015 SET-3

Consider the Bode plot shown in the figure. Assume that all the poles and zeros are real-valued. The value of f_H - f_L (in Hz) is __________.

(8970) is the correct answer.

Ques 12 GATE 2015 SET-3

The phase margin (in degrees) of the system G(s) = 10/[s(s+10)] is __________.

(84.3) is the correct answer.

Ques 13 GATE 2015 SET-3

The transfer function of a first-order controller is given as G_C(s) = K(s+a)/(s+b) where K, a and b are positive real numbers. The condition for this controller to act as a phase lead compensator is

a < b

a > b

K < ab

K > ab

(a) is the correct answer.

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