This set of VLSI Questions and Answers for Entrance exams focuses on “Technology Development in VLSI Structures-2”.
1. Which has low power dissipation?
a) CMOS
b) bipolar
c) GaAs
d) NMOS
View Answer
Explanation: CMOS has low power dissipation whereas bipolar has high and GaAs has medium power dissipation.
2. Which device has low input impedance?
a) CMOS
b) bipolar
c) GaAs
d) NMOS
View Answer
Explanation: Bipolar transistor has low input impedance and high drive current whereas CMOS and GaAs has high input impedance.
3. Which device has low noise margin?
a) CMOS
b) bipolar
c) GaAs
d) NMOS
View Answer
Explanation: GaAs has low noise margin whereas bipolar has medium noise margin. CMOS has high noise margin than the other two devices.
4. ______ has high packing density.
a) CMOS
b) bipolar
c) GaAs
d) CMOS and GaAs
View Answer
Explanation: CMOS and GaAs has high packing density whereas bipolar transistors have low packing density than CMOS and GaAs.
5. Which has low delay sensitivity to load?
a) CMOS
b) bipolar
c) GaAs
d) CMOS and GaAs
View Answer
Explanation: 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.
6. Which is direct band-gap semiconductor?
a) CMOS
b) bipolar
c) GaAs
d) bipolar and GaAs
View Answer
Explanation: GaAs is direct band-gap semiconductor and can be used as good light-emitter whereas CMOS and bipolar are indirect band-gap semiconductors.
7. 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
View Answer
Explanation: FOr very high speed operation in a semiconductor medium, three factors are significant – carrier mobility, carrier saturation velocity and existence of semi-insulating substrate.
8. MESFET is a gallium arsenide device.
a) true
b) false
View Answer
Explanation: Depletion mode and enhancement mode metal semiconductor field-effect transistor are gallium arsenide devices.
9. Second generation gallium arsenide device are
a) high electron mobility transistor
b) heterojunction bipolar transistor
c) high electron mobility & heterojunction bipolar transistors
d) none of the mentioned
View Answer
Explanation: High electron mobility transistor and heterojunction bipolar transistor are second generation gallium arsenide devices.
10. Switching delays of GaAs is in the range of
a) 40-50
b) 20-30
c) 100-120
d) 70-80
View Answer
Explanation: GaAs exhibits switching delays as low as 70 to 80 psec for a low power dissipation.
11. Which device has very high speed?
a) CMOS
b) FET
c) GaAs
d) MESFET
View Answer
Explanation: GaAs device has very high speed and low voltage swing. Bipolar device is faster than CMOS and bit slower when compared to GaAs.
12. Which has high output drive?
a) Bipolar
b) CMOS
c) FET
d) pnp
View Answer
Explanation: Bipolar transistor has high output drive. Whereas CMOS and GaAs has lower output drive comparatively.
13. In bipolar device, the relationship of gm and Vin can be described as
a) directly related
b) exponentially related
c) inversely related
d) logarithmically related
View Answer
Explanation: In bipolar device, gm is exponentially related to Vin. Mathematically it can be expressed as gm is proportional to e^(Vin).
14. Which is unidirectional device?
a) Bipolar
b) CMOS
c) FET
d) pnp
View Answer
Explanation: Bipolar device is a unidirectional device whereas CMOS and GaAs devices are bidirectional devices.
Sanfoundry Global Education & Learning Series – VLSI.
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