Explain pnp transistor circuit.

pnp transistor: A transistor consist of  three terminals. In this pnp transistor there is two blocks of p- type semiconductors that are separated by a thin layer of n-type semiconductor. This pnp transistor circuit is demonstrated in the figure below. The emitter base junction is forward biased whereas the collector base junction is reversing biased. There forward biased voltage is VEB is quite small, while the reverse biased voltage VCB is much high. Since the emitter base junction is forward biased a large number of holes (that is majority carriers) in the emitter (i.e. p- type) are pushed towards the base. It constitutes the emitter current IE. While these holes enter p- type material (base), they are subject to combine with electrons. Because the base is lightly doped and very thin, simply some electrons (less than 5 percent) combine with electrons to constitute base current that is I_B. The remaining holes (more than 95 percent) diffuse across thin base region and reach collector space charge layer. All holes then come under the affect of the negatively biased p- region and are attracted or collected through the collector. It constitutes collector current that is I_C. It is seen that almost all emitter current flows in the collector circuit. Therefore, the emitter current is the sum of collector current and base current that is I_E = I_C+ I_B.

pnp transistor circuit