# VLSI Questions and Answers – Area Capacitance

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

1. Conducting layer is separated from substrate using ____________
a) dielectric layer
b) silicon layer
c) metal layer
d) diffusion layer

Explanation: Conducting layer is separated from the substrate by using dielectric or insulating layer as both are electrical insulators that can be polarized by an applied electric field.

2. Gate to channel capacitance of 5 micron technology is _____ pF X 10(-4) (micrometer)2.
a) 1
b) 2
c) 4
d) 0.4

Explanation: Gate to channel capacitance of 5 micron technology is 4 pF X 10(-4) (micrometer)2. It is the standard typical calculated value.

3. Area capacitance of diffusion region of 2 micron technology is _____ pF X 10(-4) (micrometer)2.
a) 2
b) 2.75
c) 3.75
d) 4.75

Explanation: Area capacitane of diffusion region of 2 micron technology is 3.75 pF X 10(-4) (micrometer)2.

4. What is the relative capacitance of diffusion region of 5 micron technology?
a) 1
b) 0.25
c) 1.25
d) 2

Explanation: The relative capacitance of diffusion region of 5 micron technology is 0.25. The relative value is calculated by comparing two values of same type.

5. A feature size square has ___________
a) L > W
b) W > L
c) L = W
d) L > d

Explanation: A feature size square has L = W and its gate to channel capacitance value is called as square Cg.

6. What is the standard square Cg value of a 5 micron technology?
a) 0.01 pF
b) 0.1 pF
c) 1 pF
d) 10 pF

Explanation: The standard square Cg value of a 5 micron technology is 0.01 pF. This standard square Cg value can be calculated by using the area of standard square value and the capacitance value.

7. What is the standard square Cg value of a 1.2 micron technology?
a) 0.01 pF
b) 0.0023 pF
c) 0.023 pF
d) 0.23 pF

Explanation: The standard square Cg value of a 1.2 micron technology is 0.0023 pF.

8. Relative area for L = 20λ and W = 3λ is?
a) 10
b) 15
c) 1/15
d) 1/10

Explanation: Relative area for L = 20λ and W = 3λ is = (20λ X 3λ) / (2λ X 2λ) = 15. Relative area has no unit as two quantities of same type have been used.

9. What is the value of gate capacitance?
a) 0.25 square Cg
b) 1 square Cg
c) 1.25 square Cg
d) 1.5 square Cg

Explanation: The value of gate capacitance is one square Cg. This is the standard value.

10. What is the delay unit of 5 micron technology?
a) 1 nsec
b) 0.1 nsec
c) 0.01 nsec
d) 1 sec

Explanation: Delay unit of 5 micron technology is 0.1 nsec.

11. What is the delay unit of 1.2 micron technology?
a) 0.064 nsec
b) 0.0064 nsec
c) 0.046 nsec
d) 0.0046 nsec

Explanation: The delay unit of 1.2 micron technology is 0.046 nsec.

12. What is the transition point of an inverter?
a) Vdd
b) 0.5 Vdd
c) 0.25 Vdd
d) 2 Vdd

Explanation: The transition point of an inverter is 0.5 Vdd. The transition point is the point where different phases of same substance can be obtained in equilibrium.

13. What is the desired or safe delay value for 5 micron technology?
a) 0.3 nsec
b) 0.5 nsec
c) 0.1 nsec
d) 0.2 nsec

Explanation: The desired or safe delay value for 5 micron technology is 0.3 nsec. 