Electrical Properties of MOS and BiCMOS Circuits MCQ Quiz – Objective Question with Answer for Electrical Properties of MOS and BiCMOS Circuits MCQ MCQ
A. uniform
B. non-uniform
C. wide
D. uniform and wide
Answer: A
In the linear region of MOSFET, the channel is uniform and narrow. This is the concentration distribution.
12. When the channel pinches off?
A. Vgs > Vds
B. Vds > Vgs
C. Vds > (Vgs-Vth)
D. Vgs > (Vds-Vth)
Answer: C
In MOSFET, in the saturation region, when Vds > (Vgs – Vth), the channel pinches off that is the channel current at the drain spreads out.
13. When the threshold voltage is more, leakage current will be?
A. more
B. less
C. all of the mentioned
D. none of the mentioned
Answer: B
Increasing the threshold voltage, leads to a small leakage current when turned off and reduces current flow when turned on.
14. MOSFET is used as ___________
A. current source
B. voltage source
C. buffer
D. divider
Answer: A
MOSFET is used as a current source. A bipolar junction transistor also acts as a good current source.
15. The work function difference is negative for ____________
A. silicon substrate
B. polysilicon gate
C. silicon substrate & polysilicon gate
D. none of the mentioned
Answer: C
The work function difference between the gate and Si (Φms) is negative for silicon substrate and polysilicon gate.
16. Substrate bias voltage is positive for nMOS.
A. true
B. false
Answer: B
Substrate bias voltage Vsb is positive for pMOS and negative for nMOS.
17. According to body effect, substrate is biased with respect to ___________
A. source
B. drain
C. gate
D. Vss
Answer: A
According to the body effect, the substrate is biased with respect to the source. The body effect can be seen as a change in the threshold voltage
.
18. Increasing Vsb _______ the threshold voltage.
A. does not effect
B. decreases
C. increases
D. exponentially increases
Answer: C
Increasing the substrate bias voltage Vsb increases the threshold voltage because it depletes the channel of charge carriers.
16. Transconductance gives the relationship between ___________
A. input current and output voltage
B. output current and input voltage
C. input current and input voltage
D. output current and output voltage
Answer: B
Transconductance expresses the relationship between output current Ids and input voltage Vgs.
17. Transconductance can be increased by ___________
A. decreasing the width
B. increasing the width
C. increasing the length
D. decreasing the length
Answer: B
The transconductance gm of a MOS device can be increased by increasing its width and it does not depend on length.
18. Increasing the transconductance ___________
A. increases input capacitance
B. decreasing area occupied
C. decreasing input capacitance
D. a decrease in the output capacitance
Answer: A
Increasing the transconductance gm results in an increase in input capacitance and area occupied as it is directly proportional.
19. Ids is _______ to length L of the channel.
A. directly proportional
B. inversely proportional
C. not related
D. logarithmically related
Answer: B
Ids are inversely proportional to the length L of the channel and using this relationship strong dependence of output conductance on channel length can be demonstrated.
20. Switching speed of a MOS device depends on ___________
A. gate voltage above a threshold
B. carrier mobility
C. length channel
D. all of the mentioned
Answer: D
The switching speed of a MOS device depends on gate voltage above a threshold and on carrier mobility and inversely as the square of channel length.