GATE Electronics and Communication Test 2 Online Question Answer

1. The small-signal resistance (i.e., dV_B/dI_D) in kΩ offered by the n-channel MOSFET M shown in the figure below, at a bias point of V = 2 V is (device data for M: device Transconductance parameter k_N = μ_n C_ox (W/L) = 40μA/V², threshold voltage V = 1V, and neglect body effect and channel length modulation effects)

2. In the circuit shown below, the keen current of the ideal Zener diode is 10 mA. To maintain 5V across R, the minimum value of R in Ω and the maximum power rating of the Zener diode in mW, respectively are:

3. The impulse response of a system is u(t) = tu(t) . For an input u(t-1), the output is:

4. The bit rate of a digital communication system is R kbits/s. The modulation used is 32-QAM. The minimum bandwidth required for ISI free transmission is:

5. Let U and V be two independent and identically distributed random variables such that P(U = + 1) = P(U = -1) =1/2 . The entropy H(U + V) in bits is:

6. In a MOSFET operating in the saturation region, the channel length modulation effect causes.

7. The maximum value of θ until which the approximation sin θ = θ holds to within 10% error is:

8. The magnetically uncoupled inductive coils have Q factors q₁ and q₂ at the chosen operating frequency. Their respective resistances are R₁ and R₂. When connected in series, their effective Q factor at the same operating frequency is:

9. The current I_S in Amps in the voltage source, and voltage V_S in Volts across the current source respectively, are

10. A band limited signal with a maximum frequency of 5 kHz is to be sampled. According to the sampling theorem, the sampling frequency which is not valid is:

11. A bulb in a staircase has two switches, one switch being at the ground floor and the other one at the first floor. The bulb can be turned ON and also can be turned OFF by any one of the switches irrespective of the state of the other switch. The logic of switching of the bulb resembles.

12. Statement: You can always give me a ring whenever you need. Which one of the following is the best inference from the above statement?

13. In the circuit shown below, Q₁ has negligible collector-to- emitter saturation voltage and the diode drops negligible voltage across it under forward bias. If V_cc is + 5V, X and Y are digital signals with 0 V as logic 0 and V_cc as logic 1, then the Boolean expression for Z is:

14. Choose the grammatically CORRECT sentence:

15. A voltage 1000 sinωt Volts is applied across YZ. Assuming ideal diodes. the voltage measured across WX in Volts, is:

16. The signal flow graph for a system is given below. The transfer function Y(s)/U(s) for this system is

17. Bits 1 and 0 are transmitted with equal probability. At the receiver, the pdf of the respective received signals for both bits are shown below.
The optimum threshold to achieve minimum bit error rate (BER) is:

18. Three capacitors C, C and C whose values are 10µF, 2µF respectively, have breakdown voltages of 10V, 5V and 2V respectively. For the interconnection shown below, the maximum safe voltage in Volts that can be applied across the combination and the corresponding total charge in µC stored in the effective capacitance across the terminals are respectively.

19. The schematic of an NMOS common source stage is shown in the figure below, where part of the biasing circuits has been omitted for simplicity. For the n-channel MOSFET M, the Transconductance g_m = 1mA/V, and body effect and channel length modulation effect are to be neglected. The lower cutoff frequency in Hz of the circuit is approximately at:

20. For 8085 microprocessor, the following program is executed
MVI A, 05H;
MVI B, 05H;
PTR: ADD B;
DCR B;
JNZ PTR;
ADI 03H;
HLT;
At the end of program, accumulator contains

21. Consider a delta connection of resistors and its equivalent star connection as shown below. If all elements of the delta connection are selected by a factor k, k > 0, the elements of the corresponding star equivalent will be scaled by a factor of

22. The open-loop transfer function of a dc motor is given as ω(s)/V(s)   =   10/1 + 10s , when connected is feedback as shown below, the approximate value of K that will reduce the time constant of the closed loop system by one hundred times as compared to that of the open - loop system is:

23. A car travels 8 km in the first quarter of an hour, 6 km in the second quarter and 16 km in the third quarter. The average speed of the car in km per hour over the entire journey is:

24. The following arrangement consists of an ideal transformer and an attenuator which attenuates by a factor of 0.8. An ac voltage V = 100V is applied across WX to get an open circuit voltage V_YZ1 across YZ. Next, an ac voltage V_YZ2 = 100V is applied across YZ to get an open circuit voltage V_WX2 across WX. Then, V_YZ1/V_WX1, V_WX2/V_YZ2 are respectively.

25. Consider two identically distributed zero-mean random variables U and V. Let the cumulative distribution functions of U and 2V be F(x) and G(x) respectively. Then, for all values of x

26. In a voltage - voltage feedback as shown below, which one of the following statements is TRUE if the gain k is increased?

27. In a forward biased pn junction diode, the sequence of events that best describes the mechanism of current flow is

28. The current in the 1Ω resistor in Amps is:

29. In the circuit shown below, if the source voltage V_s = 100∠53.13º V then the Thevenin's equivalent voltage in Volts as seen by the load resistance R_L is:

30. In the circuit shown below, the silicon npn transistor Q has a very value of β. The required value of R₂ in kΩ to produce I_C = 1mA is:

31. Which one of the following statements is NOT TRUE for a continuous time causal and stable LTI system?

32. In IC technology, dry oxidation (using dry oxygen) as compared to wet oxidation (using steam or water vapour) produces

33. A polynomial f(x) = a₄x⁴ + a₃x³ + a₂x² + a₁x - a₀ with all coefficients positive has

34. For a periodic signal v(t) = 30 sin 100t + 10 cos 300t + 6 sin (500t + π/4), the fundamental frequency in rad/s

35. Two system with impulse responses h₁ (t) and h₂ (t) are connected in cascade. Then the overall impulse response of the cascaded system is given by:

36. The impulse response of a continuous time system is given by h(t) = δ(t - 1) + δ(t - 3). The value of the step response at t = 2 is:

37. In the circuit shown below the op-amps are ideal. The V_out in Volts is:

38. In the circuit shown below what is the output voltage (V_out) of a silicon transistor Q and an ideal op-amp are used?

39. Bits 1 and 0 are transmitted with equal probability. At the receiver, the pdf of the respective received signals for both bits are shown below.
If the detection threshold is 1. the BER will be

40. A system described by a linear, constant coefficient, ordinary first order differential equation has an exact solution given by y(t) for > t 0, when the forcing function is x(t) and the initial condition is y(0). If one wishes to modify the system so that the solution becomes -2y(t) for t > 0, we need to