PU CET PG 2018 Question Paper M.Tech. Microelectronics

M.Tech. Microelectronics

1. Which of the following is not associated with a PN junction?
(A) Junction Capacitance (B) Channel Length Modulation
(C) Depletion (D) Charge Storage Capacitance

2. Which material among the following possesses as excellent dielectric properties and
good reliability for use in making capacitors?
(A) Silicon monoxide (B) Silicon dioxide
(C) Tin oxide (D) Chromium oxide

3. Which model comes up with solution for quantum mechanics?
(A) Bohr’s model (B) Rutherford model
(C) Schrodinger model (D) JJ Thomson model

4. One of the following is not a semiconductor:
(A) Gallium arsenide (B) Indium
(C) Germanium (D) Silicon

5. The unit of electron mobility is:
(A) m2V-1s-1 (B) mV-1s-1
(C) Vsm-1 (D) Vms-1

6. Derive the Boolean expression for the logic circuit shown below where input is X and
output is F:

(A) F=1 (B) F=0
(C) F= (D) F=X

7. The 2's complement of 11100111 is ________.
(A) 11100110 (B) 00011001
(C) 00011000 (D) 00011010

8. Which of the following describes the operation of a positive edge-triggered D flip-flop?

(A) If both inputs are HIGH, the output will toggle.
(B) The output will follow the input on the leading edge of the clock.
(C) When both inputs are LOW, an invalid state exists.
(D) The input is toggled into the flip-flop on the leading edge of the clock and is passed
to the output on the trailing edge of the clock.
9. One application of a digital multiplexer is to facilitate:
(A) Data generation (B) Serial-to-parallel conversion
(C) Parity checking (D) Data selector
184

10. How many address bits are needed to select all memory locations in the 2118 16K × 1
RAM?
(A) 8 (B) 10
(C) 14 (D) 16

11. Output impedance of an ideal op-amp is:
(A) Infinite (B) Very high
(C) Low (D) Zero

12. A circuit whose output is proportional to the difference between the input signals is
considered to be which type of amplifier?
(A) Common-mode (B) Darlington
(C) Differential (D) Operational

11. If ground is applied to the (+) terminal of an inverting op-amp, the (–) terminal will:
(A) not need an input resistor (B) be virtual ground
(C) have high reverse current (D) not invert the signal

12. A Wien bridge oscillator uses ……………. feedback
(A) Negative Feedback (B) Positive Feedback
(C) both Negative & Positive (D) doesn’t use

13. If Barkhausen criterion is not fulfilled by an oscillator circuit, it will:
(A) Stop Oscillating (B) Produce damped waves continuously
(C) become an amplifier (D) Produce high frequency whistles

14. Discrete Fourier Transform is applied to
(A) Infinite sequences (B) Finite discrete sequences
(C) Continuous infinite signals (D) Continuous finite sequences

15. The error in the filter output that results from rounding or truncating calculations
within the filter is called
(A) Coefficient quantization error (B) Adder overflow limit cycle
(C) Round off noise (D) Limit cycles

16. In FIR filters, which among the following parameters remains unaffected by the
quantization effect?
(A) Magnitude Response (B) Phase Characteristics
(C) Amplification factor (D) Attenuation

17. Which term applies to the maintaining of a given signal level until the next sampling?
(A) Holding (B) Aliasing
(C) Shannon frequency sampling (D) "Stair-stepping"

185

18. On-off keying is the modulation scheme used for the majority of optical-fiber
communication systems. This scheme is an example of ____________________.
(A) Binary frequency shift keying (B) Binary phase shift keying
(C) Binary continuous-phase frequency shift keying (D) Binary amplitude shift keying

19. In single-mode fibers, how does the fraction of energy traveling through bound mode
appear in the cladding?
(A) As a crescent wave (B) As a gibbous wave
(C) As an evanescent wave (D) As a square wave.

20. In an optical fiber, the concept of Numerical aperture is applicable in describing the
ability of __________.
(A) Light Collection (B) Light scattering
(C) Light Dispersion (D) Light Polarization

21. Laser light is ______ emission.
(A) coherent (B) stimulated
(C) spontaneous (D) coherent & spontaneous

22. Which of the following is used as an optical transmitter on the Fiber Optical
Communications?
(A) APD (B) LSA diode
(C) PIN diode (D) LED

23. Which of the following is used as an optical receiver in fiber optics communications?
(A) APD (B) Tunnel diode
(C) LASER diode (D) LED

24. Viterbi decoding is one of the most commonly used techniques in wireless
communication, is used to decode the data encoded by ___________________.
(A) Block coding (B) CRC coding
(C) Hamming coding (D) Convolutional coding

25. ___________are used by wireless sensor node, to transmit and receive the data across
the network.
(A) Radio Transceivers (B) Transmitter
(C) Amplifier (D) Modulator

26. The main goal of the ___________is to reduce energy waste caused by idle listening,
collisions, overhearing and control overhead.
(A) IEEE802.15.4 standard (B) S-MAC protocol
(C) Flooding (D) Wireless channel

27. Each sensor has a finite sensing range, determined by the___________ floor of the
sensor.
(A) Geographical (B) Ground
(C) Noise (D) Sea

186

28. An important impairment to digital signals in a communication system is the
irregularities in timing caused by imperfections in clock extraction and waveform
regeneration. This effect is known as __________________.
(A) Aliasing (B) Attenuation
(C) Fading (D) Jitter

29. KCL is based on the fact that
(A) There is a possibility for a node to store energy.
(B) Charge accumulation is possible at node
(C) There cannot be an accumulation of charge at a node.
(D) Charge accumulation may or may not be possible at a node.

30. The basic laws for analyzing an electric circuit are:
(A) Einstein’s theory. (B) Newton’s laws.
(C) Faraday’s laws. (D) Kirchhoff’s laws.

31. If there are 5 branches and 4 nodes in graph, then the number of mesh equations that
can be formed are?
(A) 2 (B) 4
(C) 6 (D) 8

32. If the roots of an equation are real and unequal, then the response will be?
(A) critically damped (B) over damped
(C) under damped (D) damped

33. Consider the circuit shown below. Find the equivalent Thevenin’s voltage between
nodes A and B. Resistances shown in figure are in Ω.

(A) 5 V (B) 10 V
(C) 8 V (D) 8.57 V

34. The modulation index of an AM wave is changed from 0 to 1. The transmitted power is
(A) Unchanged (B) Halved
(C) Increase by 50% (D) Increase by 66.5 %

35. The early-effect in a bipolar junction transistor is caused by:
(A) Fast-turn-on (B) Fast-turn-off
(C) Large collector-bass reverse bias (D) Large emitter-base forward bias

36. In binary data transmission DPSK is preferred to PSK because
(A) a coherent carrier is not required to the generated at the receiver
(B) for a given energy per bit, the probability for zero is less
(C) the 180° phase shifts of the carrier

187

(D) more protection is provided against impulse noise

37. The Fermi energy level in a p-type semiconductor lies
(A) In the middle of the energy band (B) Near the valence band
(C) Near the conduction band (D) On the conduction band

38. In TV systems, equalising pulses are sent during
(A) Horizontal blanking (B) Vertical blanking
(C) Serrations (D) Horizontal retrace

39. The Boolean function Y= AB+ CD is to be realized using only 2-input NAND gates. The
minimum number of gated required is:
(A) 2 (B) 3
(C) 4 (D) 5

40. In standard TTL the ‘totem pole' stage refers to:
(A) The multi-emitter input stage (B) Open collector output stage
(C) The output buffer (D) The phase splitter

41. When a beam of high velocity electrons strike a metal surface, the free electrons are
ejected out of the metal. This process is known as:
(A) Secondary emission (B) Field emission
(C) Photoelectric emission (D) The phase splitter

42. The material which has the property of becoming electrically polarized in response to
an applied mechanical stress is termed as:
(A) Ferroelectric (B) Piezoelectric
(C) Optoelectronic (D) Superconducting

43. 45. The intrinsic carrier concentration of silicon sample at 300 K is 1.5x10 11 /m3. If
after doping, the number of majority carriers is 5x1020 /m3, the minority carrier
density is
(A) 4.50 x 1011 (B) 3.33x104 /m3
(C) 5.00 x1020 /m3 (D) 3.00 x105 /m3

44. In an intrinsic semiconductor the free electron concentration depends on:
(A) Effective mass of electrons only
(B) Effective mass of holes only
(C) Temperature of the semiconductor
(D) Width of the forbidden energy band of the semiconductor

45. A BJT is said to be operating in the saturation region, if
(A) Both junctions are reverse biased
(B) Base-emitter junction is R.B and base collector junction is forward biased
(C) Base-emitter junction is forward biased and base-collector junction reverse biased

188

(D) Both the junctions are forward biased

46. The Ebers-Moll model is applicable to
(A) Bipolar junction transistors (B) NMOS transistors
(C) Unipolar junction transistors (D) Both the junctions are forward biased

47. For a BJT, the common – base current gain α=0.98 and the collector base junction
reverse bias saturation current ICO= 0.6 μA. This BJT is connected in the common
emitter mode and operated in the active region with a base drive current IB=20
μA. The collector current IC for this mode of operation is:
(A) 0.98 mA (B) 0.99 μA
(C) 1.0 μA (D) 1.01 mA

48. Which of the following devices is used in the microprocessors?
(A) JFET (B) BJT
(C) MOSFET (D) CMOS

49. A junction FET can be used as a voltage variable resistor:
(A) At pinch-off condition (B) Beyond pinch-off voltage
(C) Well below pinch-off condition (D) For any value of VDS

50. The MOSFET switch in its ON-state may be considered as equivalent to:
(A) Resistor (B) Inductor
(C) Capacitor (D) Battery

51. The conduction width of FinFET is:
(A) Twice that of the fin height (B) Three times that of the fin height
(C) Independent of fin height (D) Equals to fin height

52. In the forward blocking region of a silicon controlled rectifier, the SCR is:
(A) In the OFF-state (B) In the ON-state
(C) Reverse biased (D) At the point of breakdown

53. ____ is used for protection of SCR against turn ON dv/dt and reverse recovery
transients.
(A) Circuit Breakers (B) Fast acting current limiting fuses
(C) Snubber circuits (D) Miniature Circuit Breaker

54. A TRIAC can be triggered with:
(A) Positive Pulse (B) Negative Pulse
(C) Both Positive and Negative Pulse (D) Light

55. The decibel gain in amplifiers is important because:
(A) The overall gain can be calculated by multiplying the gains of individual stages
189

(B) Value of gain is small when expressed in dB
(C) It tallies with human ear response
(D) A speaker is connected at its output

56. The cascode amplifier is a multistage configuration of:
(A) CC-CB (B) CE-CB
(C) CB-CC (D) CE-CC

57. In an R-C coupled common emitter amplifier
(A) Coupling capacitance affects the high frequency response and bypass capacitance
affects the low frequency response.
(B) Both coupling and bypass capacitances affect the low frequency response only.
(C) Both coupling and bypass capacitances affect the high frequency response only.
(D) Coupling capacitance affects the low frequency response.

58. The emitter diffusion capacitance for a transistor is:
(A) Inversely proportional to the collector current
(B) Directly proportional to the collector current
(C) Independent of the collector current
(D) Proportional to the square of collector current

59. The voltage gain of an amplifier decreases at 20 dB/decade above 100 kHz. If the
midband frequency gain is 80 dB, what is the value of the voltage gain at 2 MHz?
(A) 60 dB (B) 52 dB
(C) 54 dB (D) 64 dB

60. The light emitting diode (LED) emits light of a particular colour because
(A) It is fabricated from a fluorescent material
(B) Transition between energy levels of the carriers takes place while crossing the p
n junction.
(C) Heat generated in the diode is converted into light
(D) The band gap of the semiconductor material used in the fabrication of the diode is
equal to the energy ℎ of the light photon.

61. Photoconductive cell most popularly used for visible light spectrum uses:
(A) Germanium (B) Silicon
(C) Gallium Arsenide (D) Cadmium Sulphide

62. The contents of register (B) and accumulator (A) of 8085 microprocessor are 49H and
3AH respectively. The contents of A and the status of carry flag CY) and sign flag (S)
after executing SUB B instructions are:
(A) A=F1, CY=1, S=1 (B) A=0F, CY=1, S=1
(C) A=F0, CY=0, S=0 (D) A=1F, CY=1, S=1

190

63. Which of the following statements is true with reference to 8085 microprocessor?
(A) ROM is a Read / Write memory
(B) PC points to the last instruction that was executed
(C) Stack works on the principle of LIFO
(D) All instructions affect the flags

64. In a microprocessor, the resister which holds address of the next instruction to be
fetched is:
(A) Accumulator (B) Program Counter
(C) Stack Pointer (D) Instructor Register

65. A dynamic RAM consists of
(A) 6 transistors (B) 2 transistors and 2 capacitors
(C) 1 transistor and 1 capacitor (D) 2 capacitors only

66. An Astable multivibrator is also called
(A) Free-running (B) Edge-triggered
(C) Emitter-coupled (D) Multi

67. A sinusoidal waveform is very useful in determining the following feature of a circuit
(A) Spectrum (B) Time constant
(C) Bandwidth (D) Linearity

68. A constant current signal across a parallel RLC circuit gives and output of 1.4 volts at
the signal frequency of 3.89 kHz. At frequency of 4 kHz, output voltage will be
(A) 1 Volts (B) 2 Volts
(C) 1.4 Volts (D) 2.8 Volts

69. Which one of the following statements is correct? In the context of IC fabrication,
metallization means.
(A) Connection metallic wires
(B) Formation of interconnecting conduction pattern and bonding pads
(C) Doping SiO2 layer
(D) Covering with a metallic cap

70. Which one of the following is the most common metal for metallization in a silicon
integrated circuit?
(A) Aluminium (B) Copper
(C) Gold (D) Nickel

71. The prime use of photolithography in IC manufacturing is to selectively etch or remove

191

(A) SiO2 (B) GaAs
(C) Si (D) Ge

72. Which of the following quantities cannot be measured/determined using Hall Effect?
(A) Type of semiconductor (p or n) (B) Mobility of charge carriers
(C) Diffusion constant (D) Carrier concentration

73. What causes the piezoelectric effect?
(A) Heat or dissimilar metals (B) Pressure on a crystal
(C) Water running on iron (D) A Magnetic field

x-x-x

192