ELEX - EDC (Transistors) - A

The current flow across the base-

emitter junction of a PNP transistor:

a. mainly electrons

b. equal numbers of holes and

electrons

c. mainly holes

d. the leakage current

C

In PNP, what can you say about its

collector current?

a. no base current

b. negative with respect to source

c. flows from emitter to collector

d. dependent on emitter

C

In a transistor, the base current is

about ___ of emitter current.

a. 25%

b. 20%

c. 35%

d. 5%

D

The primary function of the bias

circuit is to:

a. hold the circuit stable at vcc

b. hold the circuit stable at

c. ensure proper gain is achieved

d. hold the circuit stable at the

designed Q-point

D

When is degeneration tolerable in

an amplifier?

a. When it is necessary to prevent

amplitude distortion.

b. If an increase in signal amplitude

aside from the rated value is needed

c. When a decrease in signal

amplitude aside from the rated value

is needed

d. If stabilit is needed

A

The disadvantage of base bias is

that:

a. it's very complex

b. it produce low gain

c. it's too beta dependent

d. it produces high leakage current

C

C

D

B

If a splash of solder shorts the

collector resistor of TSEB, the collector

voltage will:

a. Drop to zero

b. Equal the collector supply voltage

c. Stay the same

d. Double

B

The saturation current of a transistor

used in a fixed bias circuit is __ its

value used in an emitter-stabilized or

voltage-divider bias circuit for the same

values of Rc.

a. more than

b. the same as

c. less than

d. None of the above

A

What term is used to indicate current

gain in a common-collector configuration?

a. Alpha

b. Beta

c. Gamma

d. X-ray

C

A transistor has a current gain of 0.99

in the CB mode. Its current gain in the

CC mode is:

a. 100

b. 99

c. 1.01

d. 0.99

A

In a transistor-switching network,

the operating point switches from ___

to ___ regions along the load line.

a. cutoff, active

b. cutoff, saturation

c. active, saturation

d. None of the above

B

To amplify voltage, current and power

signals using BJT amplifiers, which of the

following configuration is used?

a. common collector, common base and

common emitter

b. common base, common emitter and

common collector

c. common emitter, common collector and

common base

d. common base, common collector and

common emitter

D

B

The phase shift in the common-collector

and common-base amplifier is:

a. 270 degrees

b. 180 degrees

c. 90 degrees

d. 0 degrees

D

A certain common-emitter amplifier

has a voltage gain of 100. If the

emitter-bypass capacitor is removed,

a. the circuit will become stable

b. the voltage gain will decrease

c. the voltage gain will increase

d. the Q-point will shift

B

The gain of the transistor in common

emitter amplifier circuit is 100 at a

frequency of 1000Hz. The gain is 70.7 at

335 KHz. The gain drops to 1 at 210MHz.

The alpha-cutoff is:

a. IKHz

b. 335KHz

c. 210MHz

d. none of the above

B

Manufacturers data sheets specify

transistors using ___ parameters.

a. r

b. h

c. s

d. z

B

Which of the following is referred to

as the reverse transfer voltage ratio?

a. hi

b. hr

c. hf

d. ho

B

A

Maximum power dissipation in BJT

transistor occurs at:

a. base junction

b. collector junction

c. emitter junction

d. at the pn junction

B

What two primary items determine the

class of operation of an amplifier?

a. The amount of bias and the

amplitude of the input signal

b. DC and AC analysis

c. Amplitude of the input and output

signal

d. Fidelity and Efficiency

A

Class ____ eliminates crossover

distortion found in pure class B.

a. A

b. AB

c. C

d. D

B

What is the maximum collector

efficiency of a resistance loaded

class A power amplifier?

a. 50%

b. 78.50%

c. 25%

d. 30%

C

C

A Darlington transistor has:

a. A very low input impedance

b. Three transistor

c. A very high current gain

d. One VBE drop

C

What is the key to FET operation?

a. The amount of voltage that will control

the conduction

b. Effective cross-sectional area of the

channel

c. The amount of current that will control

the conduction

d. The low input impedance compared

with the high output impedance

B

In an N-channel JFET, pinch-off occurs

when the gate bias is:

a. slightly positive

b. zero

c. slightly negative

d. very negative

D

What is the "pinch off' voltage of an

FET?

a. The voltage required for the FET to

conduct

b. The voltage required to overcome the

FET reverse bias

c. The voltage required to reduce drain

current to zero

d. The voltage required to reduce gate

voltage to zero

C

D

C

When internal temperature increases in a

power FET, the:

a. The threshold voltage increases

b. Gate current decreases

c. Drain current decreases

d. Saturation current decreases

C

For an n-channel enhancement type

MOSFET, if the source is connected at a

higher potential than that of the bulk

(VSB > 0), the threshold voltage VT of the

MOSFET will:

a. remain unchanged

b. decrease

c. change Polarity

d. increase

A

A gate to drain-connected enhancement

mode MOSFET is an example of:

a. an active load

b. a switching device

c. a three-terminal device

d. a diode

A

The threshold voltage of an n-channel

enhancement mode MOSFET is 0.5 when

the device is biased at a gate voltage of

3V. Pinch off would occur at a drain

voltage of:

a. 1.5V

b. 2.5V

c. 3.5V

d. 4.5V

B

B

An n-channel E-MOSFET conducts when

it has:

a. VGS > VP

b. an n-type inversion layer

C. VDS > 0

d. depletion layers

B

An E-MOSFET that operates at cut-

off or in the ohmic region is an

example of:

a. a current source

b. an active load

c. a passive load

d. a switching device

D

When transistors are used in digital

circuits they usually operate in the:

a. active region

b. breakdown region

c. saturation and cutoff regions

d. linear region

C