Power Electronics Question and Answers – IGBTs-1 and Answers

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

1. IGBT possess
A. low input impedance
B. high input impedance
C. high on-state resistance
D. second breakdown problems
Answer: B
Clarification: Like MOSFET IGBT possess high input impedance.

2. IGBT & BJT both posses ___
A. low on-state power losses
B. high on-state power losses
C. low switching losses
D. high input impedance
Answer: A
Clarification: Low on state power loss is one of the best parameters of both BJT & the IGBT.

3. The three terminals of the IGBT are
A. base, emitter & collector
B. gate, source & drain
C. gate, emitter & collector
D. base, source & drain
Answer: C
Clarification: IGBT is a three terminal device. It has a gate, a emitter & a collector.

4. In IGBT, the p⁺ layer connected to the collector terminal is called as the
A. drift layer
B. injection layer
C. body layer
D. collector Layer
Answer: B
Clarification: It is called as a injection layer, because it injects holes into the n^– layer.

5. The controlling parameter in IGBT is the
A. I_G
B. V_GE
C. I_C
D. V_CE
Answer: B
Clarification: The controlling parameter is the gate to emitter voltage, as the device is a voltage controlled device.

6. In IGBT, the n^– layer above the p⁺ layer is called as the
A. drift layer
B. injection layer
C. body layer
D. collector Layer
Answer: A
Clarification: It is called as the drift layer because its thickness determines the voltage blocking capabilities of the device.

7. The voltage blocking capability of the IGBT is determined by the
A. injection layer
B. body layer
C. metal used for the contacts
D. drift layer
Answer: D
Clarification: The drift layer which is a n^– layer determines the voltage blocking capabilities.

8. The controlled parameter in IGBT is the
A. I_G
B. V_GE
C. I_C
D. V_CE
Answer: C
Clarification: The controlling parameter is the gate to collector current.

9. The structure of the IGBT is a
A. P-N-P structure connected by a MOS gate
B. N-N-P-P structure connected by a MOS gate
C. P-N-P-N structure connected by a MOS gate
D. N-P-N-P structure connected by a MOS gate
Answer: C
Clarification: The IGBT is a semiconductor device with four alternating layers (P-N-P-N) that are controlled by a metal-oxide-semiconductor (MOS) gate structure without regenerative action.

10. The major drawback of the first generation IGBTs was that, they had
A. latch-up problems
B. noise & secondary breakdown problems
C. sluggish operation
D. latch-up & secondary breakdown problems
Answer: D
Clarification: The earlier IGBT’s had latch-up problems (device cannot turn off even after the gate signal is removeD., and secondary breakdown problems (in which a localized hotspot in the device goes into thermal runaway and burns the device out at high currents).