Power Electronics Question and Answers – MOSFETs-1 and Answers

Power Electronics Multiple Choice Questions on “MOSFETs-1”.

1. The MOSFET combines the areas of _______ & _________
A. field effect & MOS technology
B. semiconductor & TTL
C. mos technology & CMOS technology
D. none of the mentioned
Answer: A
Clarification: It is an enhancement of the FET devices (field effect) using MOS technology.

2. Which of the following terminals does not belong to the MOSFET?
A. Drain
B. Gate
C. Base
D. Source
Answer: C
Clarification: MOSFET is a three terminal device D, G & S.

3. Choose the correct statement
A. MOSFET is a uncontrolled device
B. MOSFET is a voltage controlled device
C. MOSFET is a current controlled device
D. MOSFET is a temperature controlled device
Answer: B
Clarification: It is a voltage controlled device.

4. Choose the correct statement(s)
i) The gate circuit impedance of MOSFET is higher than that of a BJT
ii) The gate circuit impedance of MOSFET is lower than that of a BJT
iii) The MOSFET has higher switching losses than that of a BJT
iv) The MOSFET has lower switching losses than that of a BJT
A. Both i & ii
B. Both ii & iv
C. Both i & iv
D. Only ii
Answer: C
Clarification: MOSFET requires gate signals with lower amplitude as compared to BJTs & has lower switching losses.

5. Choose the correct statement
A. MOSFET is a unipolar, voltage controlled, two terminal device
B. MOSFET is a bipolar, current controlled, three terminal device
C. MOSFET is a unipolar, voltage controlled, three terminal device
D. MOSFET is a bipolar, current controlled, two terminal device
Answer: C
Clarification: MOSFET is a three terminal device, Gate, source & drain. It is voltage controlled unlike the BJT & only electron current flows.

6. The arrow on the symbol of MOSFET indicates
A. that it is a N-channel MOSFET
B. the direction of electrons
C. the direction of conventional current flow
D. that it is a P-channel MOSFET
Answer: B
Clarification: The arrow is to indicate the direction of electrons (opposite to the direction of conventional current flow).

7. The controlling parameter in MOSFET is
A. Vds
B. Ig
C. Vgs
D. Is
Answer: B
Clarification: The gate to source voltage is the controlling parameter in a MOSFET.

8. In the internal structure of a MOSFET, a parasitic BJT exists between the
A. source & gate terminals
B. source & drain terminals
C. drain & gate terminals
D. there is no parasitic BJT in MOSFET
Answer: B
Clarification: Examine the internal structure of a MOSFET, notice the n-p-n structure between the drain & source. A p-channel MOSFET will have a p-n-p structure.

9. In the transfer characteristics of a MOSFET, the threshold voltage is the measure of the
A. minimum voltage to induce a n-channel/p-channel for conduction
B. minimum voltage till which temperature is constant
C. minimum voltage to turn off the device
D. none of the above mentioned is true
Answer: A
Clarification: It is the minimum voltage to induce a n-channel/p-channel which will allow the device to conduct electrically through its length.

10.The output characteristics of a MOSFET, is a plot of
A. Id as a function of Vgs with Vds as a parameter
B. Id as a function of Vds with Vgs as a parameter
C. Ig as a function of Vgs with Vds as a parameter
D. Ig as a function of Vds with Vgs as a parameter
Answer: B
Clarification: It is Id vs Vds which are plotted for different values of Vgs (gate to source voltage).

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