BJT Flashcards
In an n-p-n transistor, the majority
carriers in the base are
electrons
. For a transistor to function as an
amplifier
the EB junction must be forwardbiased and the CB junction must
be-biased.
Voltage-divider bias provides:
a stable Q point
A bipolar junction transistor operates
with a collector current of 1.2 A and
a base current of 50 mA. What will
the value of emitter current be?
1.25 A
On the schematic symbol of a pnp
transistor,
the arrow points in on the emitter
lead.
In a transistor, which current is the
largest?
IE
Determine RB and RC for a fixed-bias
configuration if VCC = 12 V, β= 80,
and ICQ = 2.5 mA with VCEQ =6 V.
Use standard values.
361.6 kΩ ; 2.4 kΩ
To operate properly, a transistor’s
base-emitter junction must be
forward biased with reverse bias
applied to which junction?
collector-base
For a certain BJT, the following
values are given, = 60, Iceo=1A
and Ic =1.5 mA. Compute for the
value of IE.
1.52 mA
The primary function of the bias
circuit is to
The primary function of the bias
circuit is to
A class C amplifier is driven by a
200 kHz signal. The transistor is on
for 1 µs, and the amplifier is
operating over 100 %of its load. If
IC(sat) = 100 mA and VCE(sat) = 0.2 V.
what is the average power
dissipation?
4 mW
For a typical transistor, which two
currents are nearly the same?
IC and IE.
The ends of a load line drawn on a
family of curves determine:
saturation and cutoff
Which of the following transistor
amplifier configurations provides a
180 phase shift between the ac input
and output voltages?
the common-emitter amplifier.
Which region in a transistor is the
most heavily region?
the emitter region.
Determine Ic if Ie = 2.8 mA and IB =
20 uA.
2.78 mA
. In a bipolar transistor the barrier
potential
0.7 V across each depletion layer
. Which transistor region is very thin
and lightly doped?
the base region.
A swamping resistor in a commonemitter amplifier
stabilizes the voltages gain.
reduces distortion.
Which of the following biasing
techniques produces the most
unstable Q point?
base bias.
In a class B push-pull amplifier, the
transistors are biased slightly above
cutoff to avoid
crossover distortion
When a transistor is in saturation
VCE = 0 V
Given an αdc of 0.998, determine Ic if
Ie = 4 mA.
3.992 mA
Which of the following transistor
amplifier configurations is often used
in impedance-matching applications?
The emitter follower
With voltage divider bias, how much
is the collector-emitter voltage, VCE,
when the transistor is cut off?
. VCE = VCC.
In a C-E configuration, an emitter
resistor is used for:
stabilization
A transistor is biased so that IBQ =
120 A, the following values are
given, ICBQ = 10 A and = 0.96.
Find the value of IEQ
3.25 mA
What is the biggest disadvantage of
the common-base amplifier?
its low input impedance.
In an n-p-n transistor biased for
operation in forward active region
collector is positive with respect
to base
In what operating region does the
collector of a transistor act like a
current source?
the active region.
. In a transistor, which is the largest of
all the doped regions?
the collector region.
What is the only amplifier
configuration that provides both
voltage and current gains?
The common-emitter amplifier
In a common-emitter amplifier, what
happens to the voltage gain, Av,
when a load resistor, RL, is connected
to the output?
Av decreases.
In which type of amplifier is the
input applied to the emitter and the
output taken from the collector?
The common-base amplifier
Which type of transistor amplifier is
also known as the emitter follower?
the common-collector amplifier.
. In which region of a CE bipolar
transistor is collector current almost
constant?
Active region
The endpoints of a dc load line are
labeled
IC(Sat) and VCE(off).
Which of the following conditions
are needed to properly bias an npn
transistor amplifier?
Forward bias the base/emitter
junction and reverse bias the
base/collector junction.
The ɑdc of a transistor equals
IC/LE.
In which type of amplifier is the
input applied to the emitter and the
output taken from the collector?
The common-base amplifier
. In a transistor amplifier, what
happens to the collector voltage, Vc,
when the collector current, Ic
increases?
Vc decreases.
When the collector current in a
transistor is zero, the transistor is
cut off.
Removing the emitter bypass
capacitor in a common-emitter
amplifier will
decrease the voltage gain, Av.
increase the input impedance, Zin.
With the positive probe on an NPN
base, an ohmmeter reading between
the other transistor terminals should
be:
low resistance
A bipolar junction transistor has
two p-n junctions.
Emitter bias with two power supplies
provides a
very stable Q point.
For a transistor operating in the
active region,
IC = dc X IB.
Vcc has little or no effect on the
value of IC.
In a bipolar transistor which current
is largest
emitter current
Which of the following transistor
amplifiers has the lowest output
impedance?
the common-collector amplifier.
The power dissipation in a transistor
is the product of
collector current and collector to
emitter voltage
