MOS Transistor Theory MCQ Quiz – Objective Question with Answer for MOS Transistor Theory

11. The Fermi potential of the p-type MOSFET is:

A. φfp = (kT/q)ln(ND/NA.
B. φfp = (kT/q)ln(NA/ND.
C. φfp = (kT/q)ln(NA/ni)
D. φfp = (kT/q)ln(ni/NA.

Answer: D

The Fermi potential of the p-type semiconductor is

φfp = (kT/q)ln(ni/NA)

where

ni denotes the intrinsic carrier concentration of silicon
NA is acceptor concentration
ND is Donor Concentration.

12. The Fermi potential(φfp) for the n-type MOSFET is:

A. φfp = (kT/q)ln(ND/NA)
B. φfp = (kT/q)ln(NA/ND)
C. φfp = (kT/q)ln(ND/ni)
D. φfp = (kT/q)ln(ni/ND)

Answer: C

The Fermi potential of the p-type semiconductor is

φfp = (kT/q)ln(ND/ni)

where

ni denotes the intrinsic carrier concentration of silicon
NA is acceptor concentration
ND is Donor Concentration.

13. The principle of the MOSFET operation is:

A. Control the conduction of current between the source and the drain, using the potential difference applied at the gate voltage as a control variable
B. Control the current conduction between the source and the gate, using the electric field applied at the drain voltage as a control variable
C. Control the current conduction between the PN junction, using the electric field generated by the bias voltage as a control variable
D. Control the current conduction between the PN junctions, using the electric potential generated by the gate voltage as a control variable

Answer: A

The principle of the MOSFET operation is Control the conduction of current between the source and the drain, using the potential difference applied at the gate voltage as a control variable.

By varying the gate voltage the current between the source and drain is varied.

14. The conduction of current IDS depends on:

A. Gate to source voltage
B. Drain to source voltage
C. Bulk to source voltage
D. All of the above

Answer: D

The conduction of current IDS depends on

Gate to source voltage
Drain to source voltage
Bulk to source voltage

The current depends on Vgs, Vds, Vbs, Vt, and dimensions of MOSFET.

15. The impedance at the input of the n-MOS transistor circuit is:

A. Lesser than p-MOS transistor
B. Greater than BJT transistor
C. Lesser than JFET transistor
D. Zero

Answer: B

The impedance at the input of the n-MOS transistor is more than the BJT transistor.

16. The depletion mode n-MOS differs from enhancement-mode n-MOS in:

A. Threshold voltage
B. Channel Length
C. Switching time
D. None of the mentioned

Answer: A

If n-MOS operates with negative threshold voltage then it is in depletion mode. If n-MOS operates with positive threshold voltage then it is in enhancement mode.

17. The n-MOS invertor is better than BJT in terms of:

A. Fast switching time
B. Low power loss
C. Smaller overall layout area
D. All the mentioned

Answer: D

The n-MOS invertor is better than BJT inverter due to its fast switching time, low power loss, and smaller overall layout area.

18. The n-MOS inverter consists of an n-MOS transistor is driven and

A. Resistor as a load
B. Depletion mode n-MOS as a load
C. Enhancement mode n-MOS as a load
D. Any of the mentioned

Answer: D

The n-MOS inverter consists of n-MOS and resistor or depletion mode n-MOS or enhancement mode n-MOS at the pull-up load.

19. If the n-MOS and p-MOS of the CMOS inverters are interchanged the output is measured at:

A. Source of both transistor
B. Drains of both transistor
C. Drain of n-MOS and source of p-MOS
D. Source of n-MOS and drain of p-MOS

Answer: A

When the transistors are interchanged, The drain of n-MOS is connected to the supply voltage, and the drain of p-MOS is connected to the ground. The output is measured at the source of both the transistors.

20. What will be the effect on output voltage if the positions of n-MOS and p-MOS in the CMOS inverter circuit are exchanged?

A. Output is the same
B. Output is reversed
C. Output is always high
D. Output is always low

Answer: B

When the input is low, P-MOS is ON and the output is pulled down to the ground. When the input is high, n-MOS is ON and the output is pulled up to the supply voltage.

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