BJT saturation region

We will be talking about bipolar junction transistor (BJT) saturation region (FULLY ON) in this post. Also, Links for the other two operation regions are provided immediately.

SATURATION REGION (FULLY ON)

A transistor is said to be saturated (Fully ON) when it is biased in such a way that current passes from the Emitter (E)  to the Collector (C). In NPN and PNP bipolar junction transistors (BJTs), connecting the base (B) to the collector (C) makes the PN-junction from the base (B) to the emitter (E) to be forward bias. As a result of this, the base (B) to the collector (C) of the transistor shorts thereby causing high current to flow from the emitter (E) to the collector (C). In this state the transistor is said to be saturated or fully ON. 

The below circuits explain and illustrate the operations of the saturation regions for both NPN bipolar junction transistor (BJT) and PNP bipolar junction transistor (BJT). The resistor R in the circuits limits the current that will pass through the Light Emitting Diode (LED).

NPN bjt saturation region

   PNP BJT saturation region

You might also want to read the other two bipolar junction transistor (BJT) operation regions below apart from the saturation region (fully off).

ACTIVE REGION

In active region the transistor is bias so that the base (B) measures a higher potential difference (Pd) to the emitter (E) but lower than the collector (C) to the emitter (E). In this region the transistor is always active. This is the biasing mode or region which transistor amplifiers…READ THIS

CUTOFF REGION (FULLY OFF)

In cut off or fully off region, the transistor is bias in such a way that both junctions are reverse so that no current will pass from the emitter (E) to the collector (C). In this mode, the transistor is in OFF mode.

When we study the below circuits, two PN-junction diodes are configure to form two types of layers. These are NPN layers and PNP layers. In NPN layers; P-dope is the common junction while in PNP layers; N-dope is the common junction. Both the configurations are in reverse modes. By connecting the base (B) to the emitter (E) that is to say; the base (B) is lower than the collector (C); current will not flow from the emitter (E) to the collector (C)…READ THIS

READ ALSO THESE

Leave a Comment

Your email address will not be published. Required fields are marked *