When does the transistor operate in the cutoff region?
The transistor operates in cutoff region when both the emitter and collector junctions are reverse biased. As in cutoff region, the collector current, emitter current and base currents are nil, we can write as I C = I E = I B = 0 Where I C = collector current, I E = emitter current, and I B = base current.
How is biasing done in a transistor circuit?
The supply of suitable external dc voltage is called as biasing. Either forward or reverse biasing is done to the emitter and collector junctions of the transistor. These biasing methods make the transistor circuit to work in four kinds of regions such as Active region, Saturation region, Cutoff region and Inverse active region s e l d o m u s e d.
Which is the active region of a transistor?
The transistor operates in active region when the emitter junction is forward biased and collector junction is reverse biased. In the active state, collector current is β times the base current, i.e., This is the region in which transistor tends to behave as a closed switch. The transistor has the effect of its collector and Emitter being shorted.
What happens to a transistor in saturation mode?
In saturation, the collector and emitter are, in effect, shorted together. That is the transistor behaves as though a switch has been closed between the collector and emitter [See Below Fig. ( iii )]. Note. When the transistor is in the active state, IC = IB. Therefore, a transistor acts as an amplifier when operating in the active state.
What is the linear region of the BJT?
This region is called “linear region” or “resistor region”. However, for further increasing the voltage Vds beyond a certain threshold (pinch-off) the current Id does not increase anymore (in fact, a slight increase due to channel width modulation can be observed).
What is the current in the saturation region?
The current source is set at a constant value of 20uA and the collector bias voltage is varied from 0 to 2V. “A Sweeping collector voltage 0 to 2 V with base current constant at 20 µA yields constant 2 mA collector current in the saturation region”