Heterojunction BJT – 2 MCQ’s

This set of RF & Microwave Circuit Design Multiple Choice Questions & Answers (MCQs) focuses on “Heterojunction BJT – 2″.

1. If the S11 and S22 parameters of a common emitter operated BJT is high:
a) then the output and input ports are matched well
b) there is mismatch in the ports
c) the gain of the amplifier is high
d) none of the mentioned

2. If a common emitter configuration BJT is treated as a two port network, the gain of the amplifier is roughly given by the S parameter:
a) S11
b) S12
c) S21
d) S22

3. The hybrid-π model of a BJT is useful for analysis at all frequency ranges and variation of other transistor parameters.
a) true
b) false

4. Short circuit current gain of BJT is given by the expression:
a) gm/ωC
b) ωC/ gm
c) gm/C
d) none of the mentioned

5. The current gain of a BJT ________ with frequency.
a) increases
b) decreases
c) remains constant
d) none of the mentioned

6. Hetero junction bipolar transistors have the same working principle and operation as that of a BJT.
a) true
b) false

7. The output collector to emitter current of a BJT amplifier is independent of the input base current of the amplifier.
a) true
b) false

8. If a transistor has a short circuit current gain of 25 and the capacitance measured in the hybrid-π model of the transistor was 60 pF. Then the threshold frequency of operation of the transistor is:
a) 60 MHz
b) 45.6 GHz
c) 66.3 GHz
d) 34.8 GHz

9. Advantage of HJT over BJT is that it has:
a) higher gain
b) high frequency of operation
c) sophisticated construction
d) none of the mentioned

10. The S21 parameter of a HJT increases with increase in the operating frequency of the transistor.
a) true
b) false

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