A. high gm
B. low gm
C. does not depend on gm
D. low cost
Answer: A
A fast circuit requires gm as high as possible as the switching speed depends on gate voltage above the threshold and on carrier mobility and inversely to the square of channel length.
22. Surface mobility depends on ___________
A. effective drain voltage
B. effective gate voltage
C. channel length
D. effective source voltage
Answer: B
Surface mobility is dependent on the effective gate voltage (Vgs-Vt). Electron mobility on an oriented n-type inversion layer surface is larger than that on an oriented surface.
23. What is a MOS transistor?
A. minority carrier device
B. majority carrier device
C. majority & minority carrier device
D. none of the mentioned
Answer: B
MOS transistor is a majority carrier device, in which current in a conducting channel between the source and drain is modulated by a voltage.
24. The MOS transistor is non conducting when?
A. zero source bias
B. zero threshold voltage
C. zero gate bias
D. zero drain bias
Answer: C
The MOS transistor normally is at cut-off or becomes non-conducting with zero gate bias (gate voltage-source voltage).
25. Inverters are essential for ________
A. NAND gates
B. NOR gates
C. sequential circuits
D. all of the mentioned
Answer: D
Inverters are needed for restoring logic levels for NAND and NOR gates, and sequential and memory circuits.
