BJT GIBILISCO Flashcards
1
Q
- In a PNP circuit, the collector
a has an arrow pointing inward.
b) is positive with respect to the emitter..
c.) is biased at a small reaction or the base bias.
d) is negative with respect to the emitter.
A
d) is negative with respect to the emitter.
2
Q
- In many cases, a PNP transistor can be replaced with an NPN device and the circuit will do the same thing, provided that
a) the power supply or battery polarity is reversed.
b) the collector and emitter leads are interchanged.
c) the arrow is pointing inward.
d) Forget it! A PNP transistor can never be replaced with an NPN transistor.
A
a) the power supply or battery polarity is reversed.
3
Q
- A bipolar transistor has
a) three P-N junctions.
b) three semiconductor layers.
c) two N-type lavers around a P-type laver.
d) a low avalanche voltage.
A
b) three semiconductor layers.
4
Q
- In the dual-diode model of an NPN transistor, the emitter corresponds to
a) the point where the cathodes are connected together.
b) the point where the cathode of one diode is connected to the anode of the other.
c) the point where the anodes are connected together.
d) either of the diode cathodes.
A
d) either of the diode cathodes.
5
Q
- The current through a transistor depends on
a) EC.
b) EB relative to EC.
С) IB.
d) more than one of the above.
A
d) more than one of the above.
6
Q
- with no signal input, a bipolar transistor would have the least IC when
a the emitter is grounded.
b) the E-B junction is forward-biased.
c. the E-B junction is reverse-biased.
d. the E-B current is high.
A
c. the E-B junction is reverse-biased.
7
Q
When a transistor is conducting as much as it can, it is said to be
a) in a state of cutoff
b) in a state of saturation.
c) in a state of reverse bias.
D. in a state or avalanche breakdown.
A
b) in a state of saturation.
8
Q
Refer to the curve shown in Fig. 22-12. Which operating point is best if a large amplification factor is desired with a weak signal input?
a) Point A
o Point E
c) Point C
d) Point D
A
c) Point C
9
Q
In Fig. 22-12, the forward breakover point for the E-B junction is
nearest to
a) no point on this graph.
b) point B.
c) point C.
A
b) point B.
10
Q
- In Fig. 22-12, saturation is nearest to
a) point A.
b) point B.
c) point C.
d) point D.
A
d) point D.
11
Q
- In Fig. 22-12, the greatest gain occurs at
a) point A.
b) point B.
c) point c.
d) point D.
A
c) point c.
12
Q
- In a common emitter circuit, the gain bandwidth product is
a) the frequency at which the gain is 1.
b) the frequency at which the gain is 0.707 times its value at 1 MHz.
c) the frequency at which the gain is greatest.
d) the difference between the frequency at which the gain is greatest, and the frequency at which the gain is 1.
A
a) the frequency at which the gain is 1.
13
Q
- The bipolar-transistor configuration most often used for matching a high input impedance to a low output impedance puts signal ground at
a) the emitter.
b) the base.
c) the collector.
d) any point; it doesn’t matter.
A
c) the collector.
14
Q
- The output is in phase with the input in
a) a common emitter circuit.
b) a common base circuit.
c) a common collector circuit.
d) more than one of the above.
A
d) more than one of the above.
15
Q
- The greatest possible amplification is obtained in
a) a common emitter circuit.
b) a common base circuit.
c) a common collector circuit.
d) more than one of the above.
A
a) a common emitter circuit.
16
Q
- The input is applied to the collector in
a common emitter circuit.
b) a common base circuit.
c) a common collector circuit.
d) none of the above.
A
d) none of the above.
17
Q
- The configuration noted for its stability in RF power amplifiers is the
a) common emitter circuit.
b) common base circuit.
c) common collector circuit.
d) emitter follower circuit.
A
b) common base circuit.
18
Q
- In a common base circuit, the output is taken from
a) the emitter.
b) the base.
c) the collector.
a) more than one or the above.
A
c) the collector.
19
Q
- Suppose that the input signal to a transistor amplifier results in saturation during part of the cycle. This produces
a) the greatest possible amplification.
b) reduced efficiency.
c) avalanche effect.
d) nonlinear output impedance.
A
b) reduced efficiency.
20
Q
- Suppose that the gain of a transistor in a common emitter circuit is
100 at a frequency of 1 kHz, and the gain is 70.7 at 335 kHz. The gain drops to 1 at 210 MHz. The alpha cutoff frequency is
a) 1 kHz.
b) 335 kHz.
c) 210 MHz.
d) impossible to define based on this data.
A
b) 335 kHz.
21
Q
. In a common-base transistor circuit, the output and input waves differ in phase by
(a) 1⁄4 of a cycle.
(b) 1⁄3 of a cycle.
(c) 1⁄2 of a cycle.
(d) None of the above
A
(d) None of the above
22
Q
2 . Which of the following circuit configurations do engineers sometimes use in place of conventional wire wound
transformers to match a high input impedance to a low output impedance?
(a) Common emitter
(b) Common base
(c) Common collector
(d) Any of the above
A
(c) Common collector
23
Q
3 . Current will never flow in the B-C junction of a grounded-emitter bipolar transistor when we
(a) reverse-bias the E-B junction and apply no input signal.
(b) forward-bias the E-B junction beyond forward breakover and apply no input signal.
(c) zero-bias the E-B junction and apply a strong input signal.
(d) forward-bias the E-B junction beyond forward breakover and apply
A
(a) reverse-bias the E-B junction and apply no input signal.
24
Q
21-12 Illustration for Quiz Questions 4 through 8 .
(a) a common-emitter configuration.
(b) an emitter-follower configuration.
(c) a common-base configuration.
(d) a common-collector configuration.
A
(c) a common-base configuration.
25
5 . What, if any, major errors exist in the circuit of Fig. 21-12 ?
(a) Nothing is wrong, assuming that we choose the component values properly.
(b) We should use an NPN transistor, not a PNP transistor.
(c) The power-supply polarity at the collector should be positive, not negative.
(d) We should transpose the input and output terminals.
(a) Nothing is wrong, assuming that we choose the component values properly.
26
6 . In the circuit of Fig. 21-12 , what purpose does component X serve?
(a) It keeps the signal from “shorting out” to ground.
(b) It helps to establish the proper bias at the base.
(c) It ensures that the circuit won’t break into oscillation.
(d) It keeps the base at signal ground.
(b) It helps to establish the proper bias at the base.
27
7 . In the circuit of Fig. 21-12 , what purpose does component Y serve?
(a) It keeps the input isolated from the output.
(b) It keeps the output signal from “shorting out” through the power supply.
(c) It ensures that the circuit won’t break into oscillation.
(d) It helps to establish the proper bias at the base.
(d) It helps to establish the proper bias at the base.
28
8 . In the circuit of Fig. 21-12 , what purpose does component Z serve?
(a) It helps the circuit to function as an oscillator by providing feedback.
(b) It keeps the output signal from “shorting out” through the power supply.
(c) It helps to establish the proper bias at the base.
(d) It ensures that the output wave remains in phase opposition with respect to the input wave.
(b) It keeps the output signal from “shorting out” through the power supply.
29
9 . In an emitter-follower circuit, we apply the input signal between the
(a) collector and ground.
(b) emitter and collector.
(c) base and ground.
(d) base and collector.
(c) base and ground.
30
10 . In the dual-diode model of a PNP transistor, the base corresponds to
(a) the point at which the cathodes meet.
(b) the point at which the cathode of one diode meets the anode of the other.
(c) the point at which the anodes meet.
(d) either of the anodes.
(a) the point at which the cathodes meet.
31
11 . Suppose that we encounter a schematic diagram of a complicated circuit that uses bipolar transistors. For some
reason, the draftsperson didn’t put the arrows inside the transistor symbols. Can we nevertheless differentiate
between NPN and PNP devices? If so, how?
(a) No, we can’t.
(b) Yes, we can. For a PNP device, the applied DC collector voltage is always positive with respect to the
emitter voltage, while for an NPN device, the applied DC collector voltage is always negative with respect
to the emitter voltage.
(c) Yes, we can. For a PNP device, the applied DC collector voltage is always negative with respect to the
emitter voltage, while for an NPN device, the applied DC collector voltage is always positive with respect to
the emitter voltage.
(d) Yes, we can. For a PNP device, the E-B junction is always forward-biased, while for an NPN device, the E-
B junction is always reverse-biased.
(c) Yes, we can. For a PNP device, the applied DC collector voltage is always negative with respect to the
emitter voltage, while for an NPN device, the applied DC collector voltage is always positive with respect to
the emitter voltage.
32
12 . With no signal input, a properly connected common-emitter NPN bipolar transistor would have the highest
value of I C when
(a) we forward-bias the E-B junction considerably beyond forward breakover.
(b) we connect the base directly to the negative power-supply terminal.
(c) we reverse-bias the E-B junction.
(d) we connect the base directly to electrical ground.
(a) we forward-bias the E-B junction considerably beyond forward breakover.
33
13 . Suppose that for a certain transistor at a specific constant frequency, we find that the alpha equals 0.9315. What’s the beta?
(a) We can’t determine it because our figure for the alpha makes no sense. We must have made a mistake when
we determined the alpha!
(b) 13.60
(c) 0.4823
(b) 13.60
34
14 . Suppose that for a certain transistor at a certain frequency, we find that the beta equals 0.5572. What’s the
alpha?
(a) We can’t determine it because our figure for the beta makes no sense. We must have made a mistake when
we determined the beta!
(b) 1.258
(c) 0.3578
(d) 1.795
(c) 0.3578
35
15 . Suppose that for a certain transistor at a certain frequency, we find that the alpha equals exactly 1.00. What’s
the beta?
(a) We can’t define it.
(b) 0.333
(c) 0.500
(d) 1.00
(a) We can’t define it.
36
16 . In a common-emitter circuit, we normally take the output from the
(a) emitter.
(b) base.
(c) collector.
(d) More than one of the above
(c) collector.
37
21-13 Illustration for Quiz Questions 17 through 20 .
(a) The power supply voltage is too high for any bipolar transistor to handle.
(b) We should use an NPN transistor, not a PNP transistor.
(c) The power-supply polarity at the collector should be positive, not negative.
(d) We should transpose the input and output terminals.
(c) The power-supply polarity at the collector should be positive, not negative.
38
18 . In the circuit of Fig. 21-13 , what purpose does component X serve?
(a) It keeps the signal from “shorting out” through the emitter.
(b) It helps to establish the proper bias at the collector.
(c) It keeps the signal from “feeding back” into the input device.
(d) It blocks DC to or from the external input device, while letting the AC signal pass.
(d) It blocks DC to or from the external input device, while letting the AC signal pass.
39
19 . In the circuit of Fig. 21-13 , what purpose does component Y serve?
(a) It keeps the input isolated from the output.
(b) It keeps the input signal from “shorting out” through the power supply.
(c) It keeps the emitter at signal ground, while allowing a DC voltage to exist there.
(d) It helps to establish the proper bias at the base.
(c) It keeps the emitter at signal ground, while allowing a DC voltage to exist there.
40
20 . In the circuit of Fig. 21-13 , what purpose does component Z serve?
(a) It keeps the circuit from breaking into oscillation.
(b) It blocks DC to or from the external output device while letting the AC signal pass.
(c) It matches the transistor’s impedance to the impedance of the external output device, or load.
(d) It ensures that the output wave remains in phase with the input wave.
(b) It blocks DC to or from the external output device while letting the AC signal pass.
