{"id":4698,"date":"2020-09-13T08:36:44","date_gmt":"2020-09-13T06:36:44","guid":{"rendered":"https:\/\/dcaclab.com\/blog\/?p=4698"},"modified":"2020-12-27T14:52:49","modified_gmt":"2020-12-27T12:52:49","slug":"pnp-transistor-working-and-application-explained","status":"publish","type":"post","link":"https:\/\/dcaclab.com\/blog\/pnp-transistor-working-and-application-explained\/","title":{"rendered":"PNP Transistor Working and Application Explained"},"content":{"rendered":"

A PNP transistor is nothing but a bipolar junction transistor (BJT). It is made by sandwiching an n-type semiconductor between the two p-type semiconductors. This transistor is a three-terminal device. The terminals are namely, emitter (E), base (B), and collector (C). The PNP transistor acts as two PN junction diodes<\/a> connected one after another. These diodes make junctions as are connected one after another and are called collector-base and base-emitter junction.<\/span><\/p>\n

In PNP transistors, the majority charge (current) carriers are holes and the electrons are the minority charge carriers. To understand these carriers, terminals, and many more we need to go through the basics of transistors. Thus, let us learn more about all this in the upcoming sections.\u00a0<\/span><\/p>\n

Bipolar Junction Transistor<\/span><\/h2>\n

Popularly known as BJT, is a solid-state current controlled device. It is useful in switching circuits electronically. It has three terminals in which the current applied to the base region controls the current flow in the emitter and collector.<\/span><\/p>\n

\"\"<\/p>\n

\"\"

Bipolar Junction Transistor<\/p><\/div>\n

Therefore, it\u2019s like we can control the transistor action by differing the amount of applied current <\/span>at the base terminal. Hence, the name current controlled device.\u00a0<\/span>Bipolar junction Transistor is of two types, namely, NPN and PNP. In NPN, the P-type semiconductor is sandwiched between the two N-type semiconductors. The only difference in the symbols of the two transistors is that in NPN, the current direction is from base to emitter and in PNP it\u2019s opposite, i.e., from emitter to base.<\/span><\/p>\n

PNP Transistor Construction and Symbol<\/span><\/h2>\n

In PNP the two P-type regions are there on the extreme and an N-type region is in between the two. Emitter<\/a> and collector are always on the two extremes. Therefore, in the case of PNP, the emitter and collector region connects to the P-type semiconductor and base to that with N-type.<\/span><\/p>\n

The construction can be understood by visualizing two diodes connected one after the other (see the above figure). The meeting point of the two diodes (cathode) becomes the base terminal and the two anodes at the extremes become the emitter and collector of the NPN transistor.<\/span><\/p>\n

The symbol of the PNP transistor is the same as fig. One thing to note here is the current direction in both NPN and PNP transistors. This helps a lot while solving numerical problems.\u00a0<\/span><\/p>\n

Working of PNP Transistor<\/span><\/h2>\n

The circuit connection of the PNP transistor is as below. Here the emitter region has a positive bias voltage with respect to base and collector. On the other hand, the base has a negative voltage bias with respect to the emitter. The current direction and voltage polarity are just opposite to that of the NPN transistor.\u00a0<\/span><\/p>\n

\"PNP

PNP Transistor Working<\/p><\/div>\n

Now, the necessary condition for transistor operation is that the base voltage should be more negative than that of emitter voltage. Therefore, the base-emitter junction acts as a diode here. If we apply a small amount of current in the base region then a large current flows through the emitter to the collector region. As we mostly use silicon and germanium the base voltage is 0.7 V and 0.3 V respectively.<\/span><\/p>\n