The only difference is in their biasing and the polarity of the power supply for each type. The principle of operation of NPNs and PNPs is exactly the same.

The basic principle of any BJT is to control the current of a third terminal with the voltage between the other two terminals. Here is a list of some classic general-purpose BJTs (Fig. In a PNP transistor, however, the current flows from the emitter to the collector (Fig. In an NPN transistor, the current flows from the collector (C) to the Emitter (E) (Fig. In a PNP transistor, a positive voltage is given to the emitter terminal to produce current flow from the emitter to collector. In an NPN transistor, a positive voltage is given to the collector terminal to produce a current flow from the collector to the emitter. Reverse Active region: Like active mode, the current is proportional to the base current, but flows in reverse.The transistor appears as a near short circuit between the collector and emitter terminals. Saturation region: BJT operates in this zone in switching operations.Active region: BJT operates in this zone for amplifier circuits because the transistor can act as a fairly linear amplifier.Cutoff region: BJT operates in this zone in switching operations.BJTs can operate in different modes depending on the junction bias: The junctions between N and P regions are similar to the junctions in diodes and they can be forward-biased or reverse-biased as well. 2) while the NPN transistor has one P region between two N regions (Fig. The PNP transistor has one N region between two P regions (Fig. The semiconductor physics of BJTs will not be discussed here, but it is worth mentioning that a BJT is fabricated with three separately doped regions with two junctions. The Base is responsible for controlling the transistor while the Collector is the positive lead, and Emitter is the negative lead. A transistor is an active device with three terminals, and these three terminals are known as the Emitter (E), the Base (B), and the Collector (C) (Fig. BJTs are made of doped materials and can be configured as NPN and PNP. There are two main types of transistor: bipolar junction transistors (BJTs) and field effect transistors (FETs). Let’s take a closer look at how NPN and PNP transistors work. It’s easy to remember that NPN stands for Negative-Positive-Negative and PNP stands for Positive-Negative-Positive. This simple device can be used to create complex electronic circuits, and although there are other types of transistors, bipolar junction transistors are still widely used in digital circuits.īoth are used in various amplification and modulating circuits the most frequent among its applications is being fully ON and OFF, which is referred to as switch mode. The transistor is a three-terminal electronic device that can be used to control the flow of electric current, and was the first electronic device that could amplify or switch an electric current. The transistor is probably the most important invention in electronic engineering and the basis for nearly all integrated circuits (ICs).

Transistor biasing meaning