Submicron CMOS technology is faster and small and device dimensions are closely interrelated.
2. In CMOS devices, which has slower performance?
A. n-transistor
B. p-transistor
C. all of the mentioned
D. none of the mentioned
Answer: B
In CMOS devices, p-transistors have inherently slower performance than similar n-transistors and this is due to the lower mobility of holes compared with that of the electrons.
3. As the channel length is scaled down, the influence of mobility
A. increases
B. decreases
C. remains the same
D. does not affect
Answer: B
As the channel lengths are scaled-down, the influence of mobility starts to diminish as the effects of velocity saturation begin to be felt.
4. Current drive is ______ to mobility.
A. directly proportional
B. inversely proportional
C. logarithmically proportional
D. exponentially proportional
Answer: A
The current drive is directly proportional to mobility and inversely proportional to the channel length L.
5. When velocity saturation occurs, Idsat is ______ to Vsat.
A. inversely proportional
B. directly proportional
C. logarithmically proportional
D. not related
Answer: B
When velocity saturation occurs, drive current saturation Idsat is directly related to saturation velocity. It is given as
Idsat = W × Cosx × Vsat × (Vgs-Vt).
6. Current is dependent on ________ when saturation velocity occurs.
A. mobility
B. channel length
C. saturation velocity
D. transconductance
Answer: C
When saturation velocity occurs, the current becomes independent of mobility and the channel length and it is dependent on only saturation velocity.
7. Transconductance is independent of
A. channel width
B. channel length
C. material
D. channel depth
Answer: B
Transconductance is a constant and is independent of the channel length. Current is independent of mobility and channel length.
Transconductance is an expression of the performance of a bipolar transistor or field-effect transistor (FET).
In general, the larger the transconductance figure for a device, the greater the gain(amplification) it can deliver when all other factors are held constant.
8. Velocity saturation occurs at
A. lower electric field strength in n-devices
B. higher electric field strength
C. intermittent electric field strength
D. lower electric field strength in p-devices
Answer: A
Velocity saturation occurs at lower electric field strengths in n-devices owing to their higher mobility when compared with p-devices.
9. When dimensions are scaled-down ______ tends to have a constant value.
A. current drive from p-transistors
B. current drive from n-transistors
C. voltage drive from p-transistors
D. voltage drive from n-transistors
Answer: B
When dimensions are scaled-down, the current drive from n-transistors tends to a constant value independent of channel length.
10. At ______ length, the holes start to run into velocity saturation.
A. shorter
B. larger
C. all of the mentioned
D. none of the mentioned
Answer: A
At a shorter length, the holes start to run into velocity saturation and the current drive from p-transistors does not tend to a constant value.
