Table of Contents
- 1 When base width becomes zero the effect is called?
- 2 Why base is kept very thin in transistor?
- 3 Why base width of a transistor should not be too large and also should not be too small?
- 4 When the base current of a common emitter transistor is kept at zero It operates in the?
- 5 Why width of the base regions of a transistor is kept very small compared to other regions?
- 6 What happens if base width of BJT is too large?
- 7 What happens to the depletion layer of a transistor?
- 8 Why does break down voltage decrease in reverse biased transistors?
When base width becomes zero the effect is called?
3. As we increase further the reverse bias voltage at some point effective base width approaches zero and transistor will breakdown . This phenomenon is called reach through or punch through.
When the base current of a transistor is zero the transistor is said to be?
When a transistor has zero current through it, it is said to be in a state of cutoff (fully nonconducting).
Why base is kept very thin in transistor?
The base of a transistor is lightly doped than the emitter and is made narrow so that virtually all the electrons injected from the emitter (in an npn transistor) diffuse right across the base to the collector junction without recombining with holes. That is, the base width is kept less than the recombination distance.
What is base narrowing or early effect in BJT?
The Early effect, named after its discoverer James M. Early, is the variation in the effective width of the base in a bipolar junction transistor (BJT) due to a variation in the applied base-to-collector voltage.
Why base width of a transistor should not be too large and also should not be too small?
Why the width of the base region of a transistor is kept very small compared to other regions? Base region of a transistor is kept very small and very lightly doped so as to pass most of the injected charge carriers to the collector.
What is base narrowing?
Base narrowing has two consequences that affect the current: – There is a lesser chance for recombination within the “smaller” base region. – The charge gradient is increased across the base, and consequently, the current of minority carriers injected across the emitter junction increases.
When the base current of a common emitter transistor is kept at zero It operates in the?
When the base current or input current IB = 0 μA, the transistor operates in the cut-off region. In this region, both junctions are reverse biased.
Why does collector current increase with base current?
Hello, an increase in base current means more bias to the transistor which further means collector current will also increase but till the limiting value of the transistor parameters. A transistor is made up of two PN junctions, an emitter junction and a collector junction.
Why width of the base regions of a transistor is kept very small compared to other regions?
How base width modulation affect the performance of the transistor?
Early effect or base width modulation: The early effect is the variation in the width of the base in a bipolar transistor due to a variation in the applied base-to-collector voltage. For example a greater reverse bias across the collector- base junction increases the collector-base depletion width.
What happens if base width of BJT is too large?
As the base width is increased, the base current will increase thus reducing the collector current. The collector– emitter characteristics will be more flat, thus the extrapolation of collector currents will be farther i.e. Early voltage will increase.
What happens when the transistor is cut off?
In the active state, collector current [See Below Fig ( i )] is β times the base current ( i.e. IC = IB ). If the transistor is cut-off, there is no base current, so there is no collector or emitter current.
What happens to the depletion layer of a transistor?
Consider a transistor in common base configuration biased in active region of operation. As you increase collector to base voltage that is if you more reverse bias base collector junction the depletion layer width increases as depletion layer width is proportional to reverse bias voltage.
When is the base current zero in a transistor?
When there is no base emitter current (base is connected to positive in this case) it is operating in the cutoff region and collector current is approximately zero at this point. I can see that in figure (b).
Why does break down voltage decrease in reverse biased transistors?
Also when you interchange the roles of emitter and collector with emitter base junction reverse biased then break down voltage decreases as break down voltage is inversely proportional to the amount of doping.