BJT FLOYD Flashcards
The three terminals of a bipolar junction transistor are
called
A. input, output, ground
B. base, emitter, collector
C. p,n,p
D. n,p,n
B. base, emitter, collector
- In a pnp transistor, the p-region are
A. base and emitter
B. base and collector
C. emitter and collector
C. emitter and collector
- For operation as an amplifier, the base of a npn
transistor must be
A. 0 V
B. negative with respect to the emitter
C. positive with respect to the collector
D. positive with respect to the emitter
D. positive with respect to the emitter
- The emitter current is always
A. greater than the base current
B. less than the collector current
C. greater than the collector current
D. answer a and c
D. answer a and c
- The βDC of a transistor is its
A. internal resistance
B. power gain
C. voltage gain
D. current gain
D. current gain
- If IC is 50 times larger than IB, then βDC is
A. 500
B. 0.02
C. 100
D. 50
D. 50
- The approximate voltage across the forward-biased base
emitter junction of a silicon BJT is
A. 0.3 V
B. 0.7 V
C. 0 V
D. VBB
B. 0.7 V
- The bias condition for a transistor to be used as linear
amplifier is called
A. reverse-reverse
B. forward-reverse
C. collector bias
D. forward-forward
B. forward-reverse
- If the output of a transistor amplifier is 5 V rms and the
input is 100 mV rms, the voltage gain is
A. 50
B. 500
C. 5
D. 100
A. 50
- When operated in cutoff and saturation, the transistor
acts like
A. a switch
B. a linear amplifier
C. a variable capacitor D. a variable resistor
A. a switch
- In cutoff, VCE is
A. 0 V
B. minimum
C. maximum
D. equal to VCC
E. answer a and b
F. answer c and d
F. answer c and d
- In saturation, VCE is
A. 0.7 V
B. equal to VCC
C. maximum
D. minimum
D. minimum
- To saturate a BJT,
A. IB > IC(sat)/βDC
B. IB = IC(sat)
C. VCC must be at least 10 V
D. the emitter must be grounded
A. IB > IC(sat)/βDC
- Once in saturation, a further increase in base current will
A. not affected the collector current
B. cause the collector current to decrease
C. cause the collector current to increase
D. turn the transistor off
A. not affected the collector current
- If the base-emitter junction is open, the collector voltage
is
A. floating
B. VCC
C. 0 V
D. 0.2 V
B. VCC
- The maximum value of collector current in a biased
transistor is
A. βDCIB
B. IC(sat)
C. greater than IE
D. IE - IB
B. IC(sat)
- Ideally, a dc load line is s straight line drawn on the
collector characteristics curves between
A. the Q-point and saturation
B. VCE(cut off) and IC(sat)
C. the Q-point and cut-off
D. IB = 0 and IB = IC / βDC
B. VCE(cut off) and IC(sat)
- If a sinusoidal voltage is applied to the base of a biased
npn transistor and the resulting sinusoidal collector
voltage is clipped near zero volts, the transistor is
A. being driven into saturation
B. being driven into cut off
C. operating nonlinearly
D. answer a and c
E. answer b and c
E. answer b and c
- The input resistance at the base of a biased transistor
depends mainly on
A. βDC
B. βDC and RE
C. RB
D. RE
B. βDC and RE
- In a voltage-divider biased transistor circuit such as
Figure 5 –13, RIN(base) can generally be neglected in
calculation when
A. RIN(base) > 10 R2
B. R1 «_space;R2
C. RIN(base) > R2
D. R2 > 10 RIN(base)
A. RIN(base) > 10 R2
- In a certain voltage-divider biased npn transistor, VB is
2.95 V. The dc emitter voltage is approximately
A. 2.95 V
B. 2.25 V
C. 0.7 V
D. 3.65 V
B. 2.25 V
- Voltage-divider bias
A. can be essentially independent of βDC
B. is not widely used
C. cannot be independent of βDC
D. requires fewer components than all the other
methods
A. can be essentially independent of βDC
- The disadvantage of base bias is that
A. it produces low gain
B. it is very complex
C. it produces high leakage current
D. it is too beta dependent
C. it produces high leakage current
- Emitter bias is
A. essentially independent of βDC
B. very dependent of βDC
C. provides a stable bias point
D. answer a and c
D. answer a and c
- In an emitter bias circuit, RE = 2.7 k Ω and VEE = 15 V. The
emitter current
A. is 180 mA
B. is 2.7 mA
C. is 5.3 mA
D. cannot be determined
C. is 5.3 mA
- Collector-feedback bias is
A. based on the principle of negative feedback
B. based on beta multiplication
C. based on the principle of positive feedback
D. not very stable
A. based on the principle of negative feedback
- In a voltage-divider biased npn transistor, if the upper
voltage-divider resistor (the one connected to VCC opens,
A. the transistor burns out
B. the transistor goes into saturation
C. the transistor goes into cutoff
D. the supply voltage is too high
C. the transistor goes into cutoff
- In a voltage-divider biased npn transistor, if the lower
voltage-divider resistor (the one connected to VCC) opens.
A. the collector current will decrease
B. the transistor may be driven into saturation
C. the transistor is not affected
D. the transistor may be driven into cutoff
B. the transistor may be driven into saturation
- In a voltage-divider biased pnp transistor, there is no
base current, but the base voltage is approximately
correct. The most likely problem(s) is
A. a bias resistor is open
B. the collector resistor is open
C. the base-emitter junction is open
D. the emitter resistor is open
E. answer a and c
F. answer c and d
F. answer c and d
- A small-signal amplifier
A. is always a common-emitter amplifier
B. always has an output signal in the mV range
C. uses only a small portion of its load line
D. goes into saturation once on each input cycle
C. uses only a small portion of its load line
- The parameter hfe corresponds to
A. βAC
B. βDC
C. r’c
D. r’e
A. βAC
- If the dc emitter current in a certain transistor amplifier
is 3 mA, the approximate value of r’e is
A. 3 Ω B. 3 kΩ
C. 0.33 kΩ D. 8.33 Ω
D. 8.33 Ω
- A certain common-emitter amplifier has a voltage gain of
- If the emitter bypass capacitor is removed,
A. the voltage gain will decrease
B. the voltage gain will increase
C. the circuit will become unstable.
D. the Q-point will shift
A. the voltage gain will decrease
- For a common-collector amplifier, RE = 100 Ω, r’e = 10 Ω,
and βAC = 150. The ac input resistance at the base is
A. 16.5 Ω B. 15 kΩ
C. 110 Ω D. 1500 Ω
A. 16.5 Ω
100.If a 10 mV signal is applied to the base of the emitter-
follower circuit in Question 5, the output signal is
approximately
A. 1.5 mV B. 10 mV
C. 100 mV D. 150 mV
B. 10 mV
101.For a common-emitter amplifier, RC = 1.0 kΩ, RE = 390 Ω,
and βac = 75. Assuming the RE is completely bypassed at
the operating frequency, the voltage gain is
A. 2.56 B. 66.7
C. 2.47 D. 75
B. 66.7
102.In the circuit of Question 7, if the frequency is reduced to
the point where XC(bypass) = RE, the voltage gain
A. remains the same
B. is less
C. is greater D.
B. is less
103.In a certain emitter-follower circuit, the current gain is
50. The power gain is approximately
A. 50 AV
B. 50
C. 1
D.answer a and b
D.answer a and b
104.In a darlington pair configuration, each transistor has an
ac beta of 125. If RE is 560 Ω, the input resistance is
A. 560 Ω B. 70 Ω
C. 140 kΩ D. 8.75 MΩ
D. 8.75 MΩ
105.The input resistance of a common-base amplifier is
A. the same as a CC
B. the same as a CE
C. very low
D. very high
C. very low
106.In a common-emitter amplifier with voltage-divider bias,
Rin(base) = 68 kΩ, R1 = 33 kΩ, and R2 = 15 kΩ. The total
input resistance is
A. 22.2 kΩ B. 68 kΩ
C. 8.95 kΩ D. 12.3 kΩ
C. 8.95 kΩ
107.A CE amplifier is driving a 10 kΩ load. If RC = 2.2 kΩ and
r’e = 10 Ω, the voltage gain is approximately
A. 180 B. 220
C. 10 D. 1000
A. 180
108.The overall gain found in Question 14 can be expressed
in decibels as
A. 47.0 dB B. 35.6 dB
C. 94.1 dB D. 69.8 dB
C. 94.1 dB
