GATE Electronics and Communication Test 4 Online Question Answer

1. An input x(t) = exp (-2t)u(t) + δ(t-6) is applied to an LTIsystem with impulse response h(t) = u(t). The out put is:

2. A transmission line of characteristic impedance 50W is terminated in a load impedance Z_L. The VSWR of the line is measured by 5 and the first of the voltage maxima in the line is observed at a distance of λ/4 from the load. The value of Z_L is:

3. The first six points of the 8-points DFT of a real valued sequence are 5, 1 - j3, 0, 3 - j4. The last two points of the DFT are respectively:

4. In the circuit shown below, the initial charge on the capacitor is 2.5 mC, with the voltage polarity as indicated. The switched is closed time t = 0. The current i(t) at a time t after the switched is closed is:

5. Choose the most appropriate word from the options given below to complete the following sentence:Under ethical guidelines recently adopted by the Indian Medical Association, human genes are to be manipulated only to correct diseases for which _________ treatments are unsatisfactory.

6. Drift current in the semiconductors depends upon:

7. The trignometric Fourier series of an even function does not have the:

8. When the output Y in the circuit below is 'I',  it implies that data has:

9. In the circuit shown below, the Norton equivalent current amperes with respect to the terminals P and Q is:

10. Choose the most appropriate word from the options given below to complete the following sentence:
It was her view that the country's problems had been ______ by foreign technocrats, so that to invite them to come back would be counter-productive.

11. In the circuit shown below, for the MOS transistors, μ_nC_ox = 100μA/V² and the threshold voltage V_T = 1V. The voltage V_x at the source of the upper transistor is:

12. There are two candidates P and Q in an election. During the campaign, 40% of the voters promised to vote for P, and rest for Q. However , on the day of election 15% of the voters went back on their promise to vote for P and instead voted for Q. 25% of the voters went back on their promise to vote for Q and instead voted for P. Suppose, P lost by 2 votes, then what was the total number of voters?

13. In the circuit shown below, the network N is described by the following matrix:

14. For a BJTthe common base current gain α = 0.98 and the collector base junction reverse bias saturation current I_CO = 0.6μA. This BJT is connected in the common emitter mode and operated in the active region with a base drive current I_B = 20μA. The collector current I_C for this mode of operation is:

15. Choose the word from the options given below that is most nearly opposite in the meaning to the given word:
Frequency

16. In the circuit shown below, assume that the voltage drop across a forward biased diode is 0.7 V. The thermal voltage V = kT/q = 25mV. The small signal input v_i = V_p cos (ωt) where V_p = 100mV.

The ac output voltage v_ac is:

17. The value of the integral ∮_c -3z + 4 / (z² + 4z + 5)    dz where c is the circle |z| = 1 is given by

18. The output Y in the circuit below is always '1' when

19. A Zener diode, when used in voltage stabilization circuits, is biased in:

20. The logic function implemented by the circuit below is (ground implies logic 0)

21. The channel resistance of an N-channel JFET shown in the figure below is 600Ω when the full channel thickness (t_ch) of 10μm is available for conduction. The built in voltage of the gate P⁺ N junction (V_bi) is -1 V. When the gate to source voltage (V_GS) is 0 V, the channel is depleted by 1μm on each side due to the builtin voltage and hence the thickness available for conduction is only 8μm.

The channel resistance when V_GS = -3 V is:

22. In the circuit shown below, capacitors C₁ and C₂ are very large and are shorts at the input frequency . v is a small signal input . The gain magnitude |V₀/V₁| at 10 M rad/s is:

23. For the BJT Q_L in the circuit shown below, β = ∞ V_{BEon = 0.7V ,} V_CEsat = o.7 V. The switch is initially closed. At time t = 0, the switched is open. The time t at which Q₁ leaves the active region is

24. The solution of the differential equation
 = ky, y(0) = c is

25. In the circuit given below, the value of R_L such that the power transferred to R_L is maximum is:

26. Given that f(y) = |y|/y, and q is any non-zero real number, the value of | f(q) - f(-q) is:

27. The circuit below implements a filter between the input current i_i and the output voltage v₀. Assume that the opamp is ideal. The filter implemented is a

28. The circuit shown below is driven by a sinusoidal input v_i = V_p cos (t/RC). The steady state output v₀ is:

29. An analog signal is band-limited to 4kHz, sampled at the Nyquist rate and the samples are quantized in to 4 levels. The quantized levels are assumed to be independent and equally probable. If we transmit two quantized samples per second , the information rate is _________ bits/second.

30. The channel resistance of an N-channel JFET shown in the figure below is 600Ω when the full channel thickness (t_ch) of 10μm is available for conduction. The built in voltage of the gate P⁺ N junction (V_bi) is -1 V. When the gate to source voltage (V_GS) is 0 V, the channel is depleted by 1μm on each side due to the builtin voltage and hence the thickness available for conduction is only 8μm.
The channel resistance when V_GS = 0 V is:

31. The system of equations
x + y + z = 6
x + 4y + 6z = 20
x +4y + λz = μ
has NO solution for values of λ and μ given by:

32. A measure signal m(t) = cos 200πt + 4 cosπt modulates the carrier c(t) = cos 2π f_ct where f_c = 1 MHZto produce an AM signal. For demodulating the generated AM signal using an envelope detector, the time constant RC of the detector circuit should satisfy:

33. A numerical solution of the equation f(x) = x + √x-3 = 0 can be obtained using Newton Raphson method. If the starting value is x = 2 for the iteration, the value of x that is to be used in the next step is:

34. A transmission line of characteristic impedance 50Ω is terminated by a 50Ω load. When excited by a sinusoidal voltage source at 1GHz, the phase difference between two points spaced 2mm apart on the line is found to be π/4 radians. The phase velocity of the wave along the line is:

35. A silicon PN junction is forward biased with a constant current at room temperature. When the temperature is increased by 10ºC, the forward bias voltage across the PN junction

36. In the unit step response of a network is (1 - e^-αt), then its unit impulse response is:

37. In the circuit shown below, assume that the voltage drop across a forward biased diode is 0.7 V. The thermal voltage V = kT/q = 25mV. The small signal input v_i = V_p cos (ωt) where V_p = 100mV.

The bias current I_DC through the diodes is:

38. A fair dice is tossed two times. The probability that the second toss results in a value that is higher than the first toss is:

39. The modes in a rectangular waveguide are denoted by TE_mn/TM_mn where m and n are the eigen numbers along the larger and smaller dimensions of the waveguide respectively.  Which one of the following statements is TRUE?

40. The root locus plot for a system is given below. The open loop transfer function corresponding to this plot is given by: