BJT

Question 1

In an n-p-n transistor, the majority
carriers in the base are

Answer 1

electrons

Question 2

. For a transistor to function as an
amplifier

Answer 2

the EB junction must be forwardbiased and the CB junction must
be-biased.

Question 3

Voltage-divider bias provides:

Answer 3

a stable Q point

Question 4

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?

Answer 4

1.25 A

Question 5

On the schematic symbol of a pnp
transistor,

Answer 5

the arrow points in on the emitter
lead.

Question 6

In a transistor, which current is the
largest?

Answer 6

IE

Question 7

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.

Answer 7

361.6 kΩ ; 2.4 kΩ

Question 8

To operate properly, a transistor’s
base-emitter junction must be
forward biased with reverse bias
applied to which junction?

Answer 8

collector-base

Question 9

For a certain BJT, the following
values are given,  = 60, Iceo=1A
and Ic =1.5 mA. Compute for the
value of IE.

Answer 9

1.52 mA

Question 10

The primary function of the bias
circuit is to

Answer 10

The primary function of the bias
circuit is to

Question 11

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?

Answer 11

4 mW

Question 12

For a typical transistor, which two
currents are nearly the same?

Answer 12

IC and IE.

Question 13

The ends of a load line drawn on a
family of curves determine:

Answer 13

saturation and cutoff

Question 14

Which of the following transistor
amplifier configurations provides a
180 phase shift between the ac input
and output voltages?

Answer 14

the common-emitter amplifier.

Question 15

Which region in a transistor is the
most heavily region?

Answer 15

the emitter region.

Question 16

Determine Ic if Ie = 2.8 mA and IB =
20 uA.

Answer 16

2.78 mA

Question 17

. In a bipolar transistor the barrier
potential

Answer 17

0.7 V across each depletion layer

Question 18

. Which transistor region is very thin
and lightly doped?

Answer 18

the base region.

Question 19

A swamping resistor in a commonemitter amplifier

Answer 19

stabilizes the voltages gain.
reduces distortion.

Question 20

Which of the following biasing
techniques produces the most
unstable Q point?

Answer 20

base bias.

Question 21

In a class B push-pull amplifier, the
transistors are biased slightly above
cutoff to avoid

Answer 21

crossover distortion

Question 21

When a transistor is in saturation

Answer 21

VCE = 0 V

Question 21

Given an αdc of 0.998, determine Ic if
Ie = 4 mA.

Answer 21

3.992 mA

Question 21

Which of the following transistor
amplifier configurations is often used
in impedance-matching applications?

Answer 21

The emitter follower

Question 22

With voltage divider bias, how much is the collector-emitter voltage, VCE, when the transistor is cut off?

Answer 22

. VCE = VCC.

Question 23

In a C-E configuration, an emitter resistor is used for:

Answer 23

stabilization

Question 24

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

Answer 24

3.25 mA

Question 25

What is the biggest disadvantage of the common-base amplifier?

Answer 25

its low input impedance.

Question 26

In an n-p-n transistor biased for operation in forward active region

Answer 26

collector is positive with respect to base

Question 27

In what operating region does the collector of a transistor act like a current source?

Answer 27

the active region.

Question 28

. In a transistor, which is the largest of all the doped regions?

Answer 28

the collector region.

Question 29

What is the only amplifier configuration that provides both voltage and current gains?

Answer 29

The common-emitter amplifier

Question 30

In a common-emitter amplifier, what happens to the voltage gain, Av, when a load resistor, RL, is connected to the output?

Answer 30

Av decreases.

Question 31

In which type of amplifier is the input applied to the emitter and the output taken from the collector?

Answer 31

The common-base amplifier

Question 32

Which type of transistor amplifier is also known as the emitter follower?

Answer 32

the common-collector amplifier.

Question 33

. In which region of a CE bipolar transistor is collector current almost constant?

Answer 33

Active region

Question 34

The endpoints of a dc load line are labeled

Answer 34

IC(Sat) and VCE(off).

Question 35

Which of the following conditions are needed to properly bias an npn transistor amplifier?

Answer 35

Forward bias the base/emitter junction and reverse bias the base/collector junction.

Question 36

The ɑdc of a transistor equals

Answer 36

IC/LE.

Question 37

In which type of amplifier is the input applied to the emitter and the output taken from the collector?

Answer 37

The common-base amplifier

Question 38

. In a transistor amplifier, what happens to the collector voltage, Vc, when the collector current, Ic increases?

Answer 38

Vc decreases.

Question 39

When the collector current in a transistor is zero, the transistor is

Answer 39

cut off.

Question 40

Removing the emitter bypass capacitor in a common-emitter amplifier will

Answer 40

decrease the voltage gain, Av. increase the input impedance, Zin.

Question 41

With the positive probe on an NPN base, an ohmmeter reading between the other transistor terminals should be:

Answer 41

low resistance

Question 42

A bipolar junction transistor has

Answer 42

two p-n junctions.

Question 43

Emitter bias with two power supplies provides a

Answer 43

very stable Q point.

Question 44

For a transistor operating in the active region,

Answer 44

IC = dc X IB. Vcc has little or no effect on the value of IC.

Question 45

In a bipolar transistor which current is largest

Answer 45

emitter current

Question 46

Which of the following transistor amplifiers has the lowest output impedance?

Answer 46

the common-collector amplifier.

Question 47

The power dissipation in a transistor is the product of

Answer 47

collector current and collector to emitter voltage