Why is Collector always reverse biased?

Collector is always reverse-biased w.r.t base so as to remove the charge carriers from the base-collector junction.

Which junction is reverse biased in the common collector junction?

Therefore, in common base configuration, the base-emitter junction JE is forward biased and collector-base junction JC is reverse biased. The common base configuration for both NPN and PNP transistors is shown in the below figure.

What causes the collector current to flow?

During the positive half-cycle of the signal, the base is positive with respect to the emitter and hence the base-emitter junction is forward biased. This causes a base current and much larger collector current to flow. When no signal is applied, a DC current I C will flow in the collector circuit due to the battery.

Can current flow from base to collector in an NPN transistor?

Current also flows from base to collector. Hopefully, that is also straightforward. In both cases, current is flowing across a forward biased junction when the transistor is in saturation. Due to transistor action, current also flows from collector to emitter.

Is collector-base junction always reverse biased?

The collector is always reverse biased. Its function is to remove charges from its junction with the base. In Fig. (i) The emitter is heavily doped so that it can inject a large number of charge carriers (electrons or holes) into the base.

Is collector-base junction reverse biased?

Consider an n-p-n transistor, In base emitter transistors the current is flowing forward biased, whereas, in collector and emitter transistors the current is passing in reverse biased. Thus, the emitter-base junction is forward biased and collector-base junction is reverse biased.

What is the collector current in the circuit?

A collector current is referred to when identifying the output current from the transistor to the transistor’s collector terminal. In a DC circuit, collector currents are based, for the most part, on the DC base current that is applied to the circuit and on the amplitude of the particular transistor in that circuit.

Why is Collector current negative?

With a PNP transistor, conventional current flows out of the collector so Spice might show negative current to indicate direction. With NPN, current will flow into the collector. Remember all polarities are reversed between NPN and PNP transistors.

How does current flow in NPN transistor?

In an NPN transistor, the flow of current runs from the collector terminal to the emitter terminal. In the PNP transistor, the flow of current runs from the emitter terminal to the collector terminal. As a result, a PNP transistor switches ON by a low signal, where an NPN transistor switches ON by a high signal.

How does an NPN transistor work?

The NPN transistor is designed to pass electrons from the emitter to the collector (so conventional current flows from collector to emitter). The emitter “emits” electrons into the base, which controls the number of electrons the emitter emits.