# VLSI Questions and Answers – Inverter Delays

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

1. The resistance value associated with Rp.u is?
a) 2Rs
b) Rs
c) 4Rs
d) Rs/2

Explanation: The resistance value associated with Rp.u. is 4Rs. Resistance is the measure of difficulty to pass an electric current through that material.

2. The resistance value associated with Rp.d. is?
a) 2Rs
b) Rs
c) 4Rs
d) Rs/2

Explanation: The resistance value associated with Rp.d. is 1Rs. This is the measure of difficulty to pass current through the pull-down device.

3. The overall delay of nMOS inverter pair is?
a) 4Ʈ
b) Ʈ
c) 5Ʈ
d) 2Ʈ

Explanation: The overall delay of nMOS inverter pair is Ʈ+4Ʈ = 5Ʈ. This delay is the time taken for the input signal to get inverted and arrive at the output.

4. The inverter pair delay for inverters having 4:1 ratio is?
a) 4Ʈ
b) Ʈ
c) 5Ʈ
d) 2Ʈ

Explanation: The inverter pair delay for inverters having 4:1 ratio is 5Ʈ. This measure of delay is for two inverters, in which the output of the first is given as the input for the second inverter.

5. The asymmetry of resistance value can be eliminated by ____________
a) decreasing the width
b) increasing the width
c) increasing the length
d) increasing the width

Explanation: The asymmetry of resistance value can be eliminated by increasing the width of the p-device channel.
Sanfoundry Certification Contest of the Month is Live. 100+ Subjects. Participate Now!

6. The ratio of rise time to fall time can be equated to ___________
a) βn/βp
b) βp/βn
c) βp*βn
d) βp/2βn

Explanation: The ratio of rise time to fall time can be equated to βn/βp. Rise time is the time taken by a signal to change from a specified low value to a specified high value. Fall time is the time taken for the amplitude of a pulse to decrease from a specified value to another specified value.

7. The value µn is equal to ___________
a) µp
b) 0.5µp
c) 1.5µp
d) 2.5µp

Explanation: The value of µn = 2.5 µp. This shows that µn value is greater than that of the µp.

8. Which quantity is slower?
a) rise time
b) fall time
c) all of the mentioned
d) none of the mentioned

Explanation: Rise time is slower by a factor of 2.5 than fall time.

9. Condition for achieving symmetrical operation is ___________
a) Wp = Wn
b) Wp greater than Wn
c) Wp lesser than Wn
d) Wp lesser than 2Wn

Explanation: The condition for achieving symmetrical operation is Wp = 2.5 Wn.

10. Rise time and fall time is _____ to load capacitance CL.
a) directly proportional
b) inversely proportional
c) exponentially equal
d) not related

Explanation: Rise time and fall time is directly proportional to load capacitance CL.

11. Rise time and fall time is ________ to Vdd.
a) directly proportional
b) inversely proportional
c) exponentially equal
d) not related

Explanation: Rise time and fall time are inversely proportional to Vdd. This shows that if Vdd is reduced fall time and rise time increase.

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]