[ELECS] Flashcards - BJT

Question 1

indicated as capital R with either a capital or lower case subscript depending on if it is a DC or ac resistance.

Answer 1

External Resistances

Question 2

Another application for optocouplers is as a ___ to detect a light path such as a hole in a rotating disk. In this case, the LED and phototransistor are separated by a gap.

Answer 2

transducer

Question 3

the condition in which there is maximum collector current.

Answer 3

saturation

Question 4

the state of a BJT in which the collector current has reached a maximum and is independent of the base current.

Answer 4

Saturation

Question 5

used when data or signals need to be transferred from a control circuit to a power circuit without making electrical connections between the circuits.

Answer 5

Optocouplers

Question 6

in cutofff, neither the base-emitter junction, nor the base-collector junction are ______

Answer 6

forward-biased

Question 7

3 regions of BJT

Answer 7

Emitter, base, and collector

Question 8

a transistor in which base current is produced when light strikes the photosensitive semiconductor base region.

Answer 8

Phototransistor

Question 9

the condition in which there is no base current, which results in only an extremely small leakage current or I(ceo) in the collector circuit.

Answer 9

cutoff

Question 10

a single package containing an LED and a phototransistor.

Answer 10

Optocouplers

Question 11

__ is a thin lightly doped region compared to the heavily doped ___ and moderately doped ___

Answer 11

base ; emitter ; collector

Question 12

the largest of the three semiconductor regions of a BJT.

Answer 12

Collector

Question 13

The lower end of the dc load line touches the x-axis at ___

Answer 13

cutoff

Question 14

the nonconducting state of a transistor.

Answer 14

Cutoff

Question 15

the most heavily doped of the three semiconductor regions of a BJT.

Answer 15

Emitter

Question 16

transfer a signal from one circuit to another while providing a high degree of isolation.

Answer 16

Optocouplers

Question 17

ratio of output current to input current.

Answer 17

CTR (current transfer ratio)

Question 18

produces base current when light strikes the exposed photosensitive base region,

Answer 18

Phototransistors

Question 19

can be used as a switching device in logic circuits to turn on or off current to a load.

Answer 19

BJT

Question 20

A basic test for a BJT is to use the _____ function of your DMM.

Answer 20

Diode Test

Question 21

have high gain and are more sensitive to light than photodiodes.

Answer 21

Phototransistors

Question 22

DC Quantities use _____ roman subscripts.

Answer 22

uppercase

Question 23

AC Quantities and time varying signals use _____ italic subscripts.

Answer 23

lower case

Question 24

one of the three semiconductor regions of a BJT. The base is thin and lightly doped compared to the other regions.

Answer 24

base

Question 25

A BJT amplifies AC signals by converting some of the DC power from the power supplies to AC signal power. An ac signal at the input is superimposed in the dc bias by the ______.

Answer 25

capacitive coupling

Question 26

give manufacturer's specifications for maximum operating conditions, thermal, and electrical characteristics.

Answer 26

Data Sheets

Question 27

in PNP, which of the region is positive

Answer 27

emitter

Question 28

B(DC) formula

Answer 28

I(c) / I(b)

Question 29

The ratio of collector current to base current

Answer 29

B(DC)

Question 30

are indicated as lower case quantities with a prime and an appropriate subscript.

Answer 30

Internal transistor resistances

Question 31

In ___, an increase of base current has no effect on the collector current and the relation IC = βDCIB is no longer valid.

Answer 31

saturation

Question 32

represent the circuit that is external to the transistor

Answer 32

DC Load Line

Question 33

When a BJT is in saturation, the ____

Answer 33

collector current does not change with an increase in base current

Question 34

In normal operation, the ____ is forward-biased and the ____ is reverse-biased.

Answer 34

base-emitter ; base-collector

Question 35

It is drawn by connecting the saturation and cutoff points

Answer 35

DC Load Line

Question 36

The characteristic curves for a phototransistor are based on _____ to the base

Answer 36

light flux (mW/cm2)

Question 37

the ratio of dc collector current to the dc base current in a BJT; current gain from base to collector.

Answer 37

Beta

Question 38

in NPN, which of the region is negative

Answer 38

emitter

Question 39

To test the base-emitter junction of a BJT, connect the positive lead to the ____ and the negative lead to the ____

Answer 39

base ; emitter

Question 40

a transistor constructed with three doped semiconductor regions separated by two pn junctions.

Answer 40

BJT (Bipolar Junction Transistor)