VLSI Questions and Answers – CMOS Inverter

This set of VLSI Multiple Choice Questions & Answers (MCQs) focuses on “CMOS Inverter”.

1. CMOS inverter has ______ regions of operation.
a) three
b) four
c) two
d) five
View Answer

Answer: d
Explanation: CMOS inverter has five distinct regions of operation which can be determined by plotting CMOS inverter current versus Vin.

2. If n-transistor conducts and has large voltage between source and drain, then it is said to be in _____ region.
a) linear
b) saturation
c) non saturation
d) cut-off
View Answer

Answer: b
Explanation: If n-transistor conducts and has large voltage between source and drain, then it is in saturation.

3. If p-transistor is conducting and has small voltage between source and drain, then it is said to work in ________
a) linear region
b) saturation region
c) non saturation resistive region
d) cut-off region
View Answer

Answer: c
Explanation: If p-transistor is conducting and has small voltage between source and drain, then it is said to be in unsaturated resistive region.
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4. In the region where inverter exhibits gain, the two transistors are in _______ region.
a) linear
b) cut-off
c) non saturation
d) saturation
View Answer

Answer: d
Explanation: In the region where the inverter exhibits gain, the two transistors n and p operates in saturation region.

5. If both the transistors are in saturation, then they act as ________
a) current source
b) voltage source
c) divider
d) buffer
View Answer

Answer: a
Explanation: When both the transistors are in saturation, then act as current sources so that the equivalent circuit is two current sources between Vdd and Vss.

6. If βn = βp, then Vin is equal to ________
a) Vdd
b) Vss
c) 2Vdd
d) 0.5Vdd
View Answer

Answer: d
Explanation: If βn = βp, then Vin = 0.5Vdd which implies that the changeover between logic levels is symmetrically disposed about the point.

7. Mobility depends on ________
a) Transverse electric field
b) Vg
c) Vdd
d) Channel length
View Answer

Answer: a
Explanation: Mobility is affected by the transverse electric field and thus also depends on Vgs and the mobility of p-device and n-device are inherently unequal.
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8. In CMOS inverter, transistor is a switch having ________
a) infinite on resistance
b) finite off resistance
c) buffer
d) infinite off resistance
View Answer

Answer: b
Explanation: In CMOS inverter, transistor is a switch having finite on resistance and infinite off resistance.

9. CMOS inverter has ______ output impedance.
a) low
b) high
c) very high
d) none of the mentioned
View Answer

Answer: a
Explanation: CMOS inverter has low output impedance and this makes it less prone to noise and disturbance.
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10. What is the input resistance of CMOS inverter?
a) high
b) low
c) very low
d) none of the mentioned
View Answer

Answer: a
Explanation: Input resistance of CMOS inverter is extremely high as it is a perfect insulator and draws no dc input source.

11. Increasing fan-out ____________ the propagation delay.
a) increases
b) decreases
c) does not affect
d) exponentially decreases
View Answer

Answer: a
Explanation: In CMOS inverter, increasing the fan-out also increases the propagation delay. Fan-out is a term that defines the maximum number of digital inputs that the output of a single logic gate can feed.

12. Fast gate can be built by keeping ________
a) low output capacitance
b) high on resistance
c) high output capacitance
d) input capacitance does not affect speed of the gate
View Answer

Answer: a
Explanation: Fast gate can be built by keeping the output capacitance small and by decreasing the on resistance of the transistor.

Sanfoundry Global Education & Learning Series – VLSI.

To practice all areas of VLSI, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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