# VLSI Questions and Answers – MOS Circuit Scaling – 1

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This set of VLSI Multiple Choice Questions & Answers (MCQs) focuses on “MOS Circuit Scaling – 1”.

1. The basic figures of merit for MOS devices are
a) Minimum Feature size
b) Low Power dissipation
c) Maximum operational frequency
d) All of the mentioned

Explanation: All the mentioned are the basic figures of merit for MOS devices.

2. For the constant field model, the scaling factors β and α are related as:
a) β = α
b) α = 2β
c) β = 1
d) β = α = 0

Explanation: In Constant field model, β = α.

3. In Constant Voltage model, the scaling factors β and α are related as:
a) β = α
b) α = 2β
c) β = 1
d) β = α = 1

Explanation: In Constant Voltage model, β = 1.

4. The scaling factor for the supply voltage VDD is:
a) 1
b) 0
c) 1/α
d) 1/β

Explanation: The supply voltage VDD has the scaling factor of 1/β.

5. The scaling factor of length and width of the channel are:
a) 1, 1
b) 1/α, 1/β
c) 1/α, 1/α
d) 1/β, 1/β

Explanation: The scaling factor of length is 1/α, and scaling factor for width is 1/α.

6. The third type of scaling model is:
a) λ-based model
b) µm based model
c) combined voltage and dimension model
d) combined voltage and electric field model

Explanation: The third model is known as the combined voltage and dimensions model proposed by Bergmann in 1991.

7. The scaling factor of gate area in constant voltage model is:
a) 1/α2
b) 1/β2
c) 1
d) All of the mentioned

Explanation: The gate area = L.W, therefore scaling factor = 1/α2.

8. The scaling factor of Gate Capacitance per unit area is:
a) 1/β
b) 1/α
c) β
d) α

Explanation: Gate capacitance per unit area has the scaling factor of β.

9. The scaling factor of Gate capacitance is:
a) 1/β
b) 1/α
c) β/α2
d) α/β2

Explanation: The scaling factor of Gate capacitance is β/α2.

10. In Constant voltage model the gate capacitance is scaled by a factor of:
a) 1/β2
b) 1/α2
c) β/α2
d) α/β2

Explanation: Since β is 1.

11. The parasitic Capacitance has the scaling factor:
a) Equal to gate capacitance
b) 1/α2
c) 1/α
d) 1/β

Explanation: Parasitic capacitance is scaled by 1/α.

12. The carrier density in channel in constant voltage model is scaled as:
a) 1/β
b) 1
c) β
d) All of the mentioned

Explanation: Carrier density is scaled as 1, since in constant voltage model β = 1, therefore all are correct.

13. Carrier density is measured as:
a) Average charge per unit area in the channel in ‘OFF’ state
b) Average charge per unit area in the channel in ‘ON’state
c) Average charge per unit area in the gate oxide
d) None of the mentioned

Explanation: Carrier density is the Average charge per unit area in the channel in ‘ON’ state.

14. Channel resistance is scaled as:
a) 1/α2
b) 1/β
c) 1/α
d) 1

Explanation: Channel resistance is scaled by the factor of 1.

15. The scaling factor of Gate delay in Constant field model is:
a) 1/α2
b) 1
c) 1/α
d) β/α 