What is active mode of BJT?
A transistor is said to be in its active mode if it is operating somewhere between fully on (saturated) and fully off (cutoff). Base current regulates collector current. By regulate, we mean that no more collector current can exist than what is allowed by the base current.
What are the properties of a BJT?
A bipolar junction transistor (BJT) has three terminals, called base, collector, and emitter. The BJT exhibits a tremendously useful property: a small current flowing into the base causes a much larger current to flow into the collector.
What are the four modes of operation in a BJT?
In saturation mode, both of collector to base and emitter to base is forward bias. In forward bias condition, current flow through the device, so electric current flow through the transistor….BJT modes of operation
- Cute of mode.
- Saturation mode.
- Active mode.
What are the three modes of operation for a BJT?
We will find that the Reverse Active mode is of limited usefulness, and thus the three basic operating modes of a BJT are Cutoff, Active, and Saturation.
When a BJT operates in forward active mode?
In the active mode, one junction (emitter to base) is forward biased and another junction (collector to base) is reverse biased. In other words, if we assume two p-n junctions as two p-n junction diodes, one diode will be forward biased and another diode will be reverse biased.
What is the basic difference between forward active and reverse active mode of a transistor?
Just as saturation is the opposite of cutoff, reverse active mode is the opposite of active mode. A transistor in reverse active mode conducts, even amplifies, but current flows in the opposite direction, from emitter to collector. The downside to reverse active mode is the β (βR in this case) is much smaller.
What happens active region?
The region between cut off and saturation is known as active region. In the active region, collector-base junction remains reverse biased while base-emitter junction remains forward biased. Consequently, the transistor will function normally in this region.
Why BJT is called bipolar?
Bipolar transistors are a type of transistor composed of pn junctions, which are also called bipolar junction transistors (BJTs). Whereas a field-effect transistor is a unipolar device, a bipolar transistor is so named because its operation involves two kinds of charge carriers, holes and electrons.
What is the biasing condition for a BJT to operate in an active region?
For the BJT to operate in the active region, the condition is that the base-emitter junction should be forward-biased while the base-collector junction is reverse-biased.
What does active mode mean?
Active mode is when the Base-Emitter junction is forward biased and the Base-Collector Junction is Reverse biased. For the npn this means that the Base has a higher potential than the Emitter and a lower potential than the collector.
What are the applications of active region of transistor?
Transistor biasing
EMITTER JUNCTION | COLLECTOR JUNCTION | REGION OF OPERATION |
---|---|---|
Forward biased | Forward biased | Saturation region |
Forward biased | Reverse biased | Active region |
Reverse biased | Forward biased | Inverse active region |
Reverse biased | Reverse biased | Cutoff region |
What is active region and saturation region?
a)When both collector-base & base-emitter junction is reverse biased, it is the active region. b)When both collector-base & base-emitter junction is forward biased, it is the saturation region.
What do you mean by reverse active in BJT?
There are two types of BJTs — NPN and PNP.
Why BJT is a current control device?
Bjt is current controlled device because by varying input current the output current is varied.
How to determine BJT switching time?
– The state where both junctions of transistor base-emitter and base-collector are in reverses biased condition called a cutoff mode of a diode. – In this case voltage across the base-emitter is less that does not allow current to flow from collector to emitter. – In this state, VCE is equal to the VCC.
What are the advantages of BJT over CMOS?
advantages of bjt. bjt is bipolar device. cmos is from mos family and its unipolar. bjt is current control device. cmos is voltage control device. bjt is used for high current application. cmos is used for high voltage. bjt has not high input impedance. cmos has high input impedace.