Ultra-Fast VLSI Circuits and System MCQ Quiz – Objective Question with Answer for Ultra-Fast VLSI Circuits and System

61. Silicon has a greater density than GaAs.

A. true
B. false

Answer: B

GaAs have a greater density than silicon. The density of silicon is 2.33 gm/cm3 whereas for GaAs it is 5.32 gm/cm3.

 

62. Which has a low breakdown field?

A. silicon
B. GaAs
C. gallium
D. silicon and gallium

Answer: A

Silicon has a low breakdown field in the range of 3×105 V/cm whereas for GaAs it is 4×105 V/cm.

 

63. Which has a greater effective electron mass?

A. silicon
B. GaAs
C. free electron
D. gallium

Answer: A

Silicon has a greater effective electron mass than GaAs. Silicon has electron mass in the range of 0.97 times the mass of the free electron.

 

64. Which has low power dissipation?

A. CMOS
B. bipolar
C. GaAs
D. NMOS

Answer: A

CMOS has low power dissipation whereas bipolar has high and GaAs have medium power dissipation.

 

65. Which device has low input impedance?

A. CMOS
B. bipolar
C. GaAs
D. NMOS

Answer: B

A bipolar transistor has low input impedance and high drive current whereas CMOS and GaAs have high input impedance.

 

66. Which device has a low noise margin?

A. CMOS
B. bipolar
C. GaAs
D. NMOS

Answer: C

GaAs have a low noise margin whereas bipolar has a medium noise margin. CMOS has high noise margin than the other two devices.

 

67. ______ has a high packing density.

A. CMOS
B. bipolar
C. GaAs
D. CMOS and GaAs

Answer: D

CMOS and GaAs have high packing density whereas bipolar transistors have low packing density than CMOS and GaAs.

 

68. Which has low delay sensitivity to load?

A. CMOS
B. bipolar
C. GaAs
D. CMOS and GaAs

Answer: B

Bipolar transistors have low delay sensitivity to load and fan-out whereas CMOS and GaAs have high delay sensitivity to load, fan-in, and fan-out.

 

69. Which is a direct band-gap semiconductor?

A. CMOS
B. bipolar
C. GaAs
D. bipolar and GaAs

Answer: C

GaAs is a direct band-gap semiconductors and can be used as a good light-emitter whereas CMOS and bipolar are indirect band-gap semiconductors.

 

70. Factors significant in high-speed semiconductors are

A. carrier mobility
B. carrier saturation velocity
C. existence of semi-insulating substrate
D. all of the mentioned

Answer: D

For very high-speed operation in a semiconductor medium, three factors are significant – carrier mobility, carrier saturation velocity, and the existence of a semi-insulating substrate.

 

71. MESFET is a gallium arsenide device.

A. true
B. false

Answer: A

Depletion mode and enhancement mode metal-semiconductor field-effect transistors are gallium arsenide devices.

 

72. Second-generation gallium arsenide devices are

A. high electron mobility transistor
B. heterojunction bipolar transistor
C. high electron mobility & heterojunction bipolar transistors
D. none of the mentioned

Answer: C

High electron mobility transistor and heterojunction bipolar transistor are second-generation gallium arsenide devices.

 

73. Switching delays of GaAs are in the range of

A. 40-50
B. 20-30
C. 100-120
D. 70-80

Answer: D

GaAs exhibit switching delays as low as 70 to 80 per sec for low power dissipation.

 

74. Which device has a very high speed?

A. CMOS
B. FET
C. GaAs
D. MESFET

Answer: C

GaAs device has very high speed and low voltage swing. A bipolar device is faster than CMOS and a bit slower when compared to GaAs.

 

75. Which has high output drive?

A. Bipolar
B. CMOS
C. FET
D. PNP

Answer: A

A bipolar transistor has a high output drive. Whereas CMOS and GaAs have lower output drive comparatively.

 

76. In a bipolar device, the relationship of gm and Vin can be described as

A. directly related
B. exponentially related
C. inversely related
D. logarithmically related

Answer: B

In bipolar devices, gm is exponentially related to Vin. Mathematically it can be expressed as gm is proportional to e(Vin).

 

77. Which is the unidirectional device?

A. Bipolar
B. CMOS
C. FET
D. PNP

Answer: A

A bipolar device is a unidirectional device whereas CMOS and GaAs devices are bidirectional devices.

 

78. The gallium arsenide field-effect transistor is ________ majority carrier device.

A. bulk current insulation
B. bulk current conduction
C. bulk voltage insulation
D. bulk voltage conduction

Answer: B

The gallium arsenide field-effect transistor is a bulk current-conduction majority carrier device and is fabricated from bulk gallium arsenide.

 

79. Method used for fabrication of GaAs FET is

A. ion implantation
B. disposition
C. diffusion
D. conduction

Answer: A

The methods used for the fabrication of gallium arsenide field-effect transistors are high-resolution photolithography and ion implantation.

 

80. How many masking stages does fabrication of GaAs FET require?

A. five
B. four
C. ten
D. eight

Answer: D

The fabrication of GaAs field-effect transistor requires six to eight masking stages and processing is relatively simple.

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