A. increases
B. decreases
C. remains the same
D. delay becomes zero
Answer: A
Pd is minimized by increasing Zp.d. Large Zp.d. requires large Zp.u. which results in an increase in delay D of the inverter pair.
22. For minimum D which relation is chosen?
A. Zp.u. = 1/2k
B. Zp.u. = k
C. Zp.d. = 1/k
D. Zp.d. = 1
Answer: C
For minimum D, Zp.u. is 1 and Zp.d. is equal to 1/k with Wp.u. = 2λ and Wp.d. = k × 2λ.
23. Noise margin measures the changing strength of
A. input voltage
B. output voltage
C. threshold voltage
D. supply voltage
Answer: A
Noise margin measures by how much the input voltage can change without disturbing the present logic output state.
24. Which has better noise margins?
A. nMOS
B. pMOS
C. CMOS
D. BiCMOS
Answer: C
CMOS has better noise margins than nMOS especially at low conditions because ratio adjustment is easier in CMOS.
25. A 4-bit processor has two buses which are
A. unidirectional
B. bidirectional
C. one unidirectional and one bidirectional
D. more than two buses
Answer: C
A 4-bit processor has two buses one is bidirectional to carry operand and output to shifter and register array and another bus is unidirectional to carry input.
26. The IN and OUT bus lines relative positions are interchanged to
A. match height
B. match length
C. match width
D. match thickness
Answer: A
The IN and OUT bus line’s relative positions are interchanged to make the cell stretchable and to match the height of the block and spacings.
27. The IN and OUT bus lines should be in
A. metal
B. polysilicon
C. diffusion
D. silicon
Answer: A
The IN and OUT bus lines should be in metal rather than diffusion or polysilicon to mate with the bus structures of other blocks.
28. Extensions are
A. vertical
B. horizontal
C. diagonal
D. haphazard
Answer: B
Extensions are horizontal or parallel to the stratified unit and rifts are described as extension zones.
29. Rifts and extensions should be placed in
A. The minimum amount of geometry
B. The maximum amount of geometry
C. in slopes
D. anywhere in the layout
Answer: A
Rifts and extensions should be placed where they cut a minimum amount of simple geometry, one in polysilicon and one in diffusion.
30. Rifts are used for smooth flow through buses.
A. true
B. false
Answer: A
Rifts are used for smooth flow through buses as suggested and hence one is used in polysilicon and the other in diffusion.
