Lesson 7 Flashcards
A current-controlled, three-terminal semiconductor device used for the control and amplification of electronic circuitry is called a(n) ? .
bipolar junction transistor
The bipolar junction transistor is made up of either a NPN junction or a PNP junction.
true
The relationship between the emitter current and the collector current in a BJT is called ? .
The emitter current divides into the base and collector current; therefore, it is this relationship that is labeled alpha. This relationship can be confusing to the student. The relationship between base current and collector current can be expressed as:
a=Ic/Ie
a=Ic/(Ib+Ic)
At ? , the transistor passes nearly no current across E-C (like an open switch).
cutoff
The measured voltage across E-C nearly equals VCC. Both B-E and B-C are reverse biased.
During ? , B-E is forward biased and C-E is reverse biased.
saturation
Which of the transistor configurations has a voltage phase reversal due to the collector voltage being 180° out of phase with the input base voltage?
common emitter
In normal operation of the BJT type transistor, the B-E junction must be reverse biased, and the C-B junction must be forward biased.
false
For the BJT type transistor, the B-E junction must be forward biased, and the C-B junction must be reverse biased
Which of the following formulas represents emitter current during normal operation?
Ie=Ic+Ib
The ? is the most popular configuration, and application is universal.
common emitter
Beta is the amount of DC voltage gain in a transistor. It is a relationship between the DC collector voltage to DC base voltage.
false
Beta is the amount of DC current gain in a transistor. It is a relationship between the DC collector current to DC base current.
If beta of a transistor is 200 and IC is 12 milliamps, what is the base current in microamps?
Ib=Ic/beta
Which transistor configuration is very useful as an isolation amplifier and is often called an emitter follower?
Common collector
If the NPN transistor in the image was replaced with a PNP type, what changes to the circuit would be necessary?
The polarity of both power sources would have to be reversed
The PNP transistor is based on hole current where the NPN transistor is based on electron current.
true
Why is the NPN transistor more widely used than the PNP?
Due to the NPN’s popularity, it is less expensive.
Manufacturers have more NPN types to offer, which allows circuit designers better flexibility.
The NPN is based on negative ground, which is more common than positive ground systems.
