PNP Transistors

PNP transistor

A PNP transistor can be defined as: one n-type material is doped with two p-type materials, such type of transistor is called a PNP transistor. It is a current control device. A small amount of base current controls both the emitter and collector currents. A PNP transistor has two crystal diodes connected back to back. The left side of the diode is called the emitter-base diode and the right side of the diode is called the collector-base diode.

The current in the hole consists of most of the carriers of the PNP transistor. The current inside a transistor is created by the movement of holes, while the current in the transistor leads is created by the flow of electrons. A PNP transistor turns on when a small current flows through its base. Current in a PNP transistor flows from emitter to collector.

The letter of the PNP transistor indicates the voltage required by the emitter, collector and base of the transistor. The base of a PNP transistor is always negative with respect to the emitter and collector. In PNP transistors, electrons are taken from the base terminal. The current entering the base is amplified to the collector terminal.

The working principle of PNP transistor:
Since the emitter pushes holes in the base region, the emitter-base junction is connected in forward bias. These holes constitute the emitter current. When these electrons enter the N-type semiconductor material or matrix, they combine with electrons. The base of the transistor is very thin and lightly doped. Therefore, only a few holes are combined with electrons, and the rest of the holes move to the collector space charge layer. Thus a base current is generated.
  Reverse bias is used to connect the collector-base region. When the depletion region is exposed to a negative polarity, the collector collects or attracts the holes that accumulate around the depletion region. This creates a collector current. The collector current IC allows the entire emitter current to flow.
The structure of the PNP transistor:
The structure of a PNP transistor is shown in the figure below. The emitter-base junction is forward-biased and the collector-base junction is reverse-biased. The emitter connected in forward bias attracts electrons to the cell, making up the current flow from the emitter to the collector.
The base of the transistor is always positively charged with respect to the collector so that holes from the collector junction cannot enter the base. And the base-emitter stays in front, so holes from the emitter region go into the base and then pass through the depletion region into the collector region. The doped semiconductor is found in three parts of the transistor. One side is the emitter and the other side is the collector. The base refers to the area in the middle. The three components of the transistor are described in detail below.