250+ TOP MCQs on Metal Oxide Semiconductor (MOS) Transistor – 2 and Answers

VLSI Multiple Choice Questions on “Metal Oxide Semiconductor (MOS) Transistor – 2”.

1. The current through the n-MOS transistor will flow when:
A. Vgs > Vtreshold, Vds=0
B. Vgd < Vtreshold, Vds=0
C. Vgs > Vtreshold, Vds>0
D. Vgd > Vtreshold, Vds<0
Answer: C
Clarification: The current flows through the n-MOS transistor when Vgs > Vtreshold, Vds>0.

2. The p-MOS Transistor is said to be in Saturation mode when:
A. Vdsp > Vgsp – Vtp
B. Vgsp < Vdsp –Vtp
C. Vgsp > Vtp
D. Vdsp < Vgsp – Vtp
Answer: D
Clarification: The pMOS transistor is in Saturation mode when Vdsp < Vgsp – Vtp and Vgsp < Vtp.

3. 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
Clarification: 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.

4. 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
Clarification: 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.

5. 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
Clarification: By varying the gate voltage the current between the source and drain are varied.

6. The conduction of current IDS depends on:

i) Gate to source voltage
ii) Drain to source voltage
iii) Bulk to source voltage
iv) Threshold voltage
v) Dimensions of MOSFET

A. Only i
B. Only i, ii and iii
C. Only v
D. All of the mentioned
Answer: D
Clarification: The current depends on Vgs, Vds, Vbs, Vt and dimensions of MOSFET.

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

8. 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
Clarification: 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.