Thursday, September 26, 2013

Electronic Semikonductor Component of Transistor NPN-PNP and How Its Works

Robometricschool. - One semiconductor component that very important when we design electronic circuit schematic for our project is TRANSISTOR. In this time we want to describe about Types of transistor NPN and PNP and How its Works.

Description of Transistor

A transistor is a semiconductor device that is used as an amplifier, as the circuit breaker and junction (switching), voltage stabilization, signal modulation or as other functions. Such transistors can function electric faucet, which is based on input current (BJT) or input voltage (FET), enabling highly accurate power flux from the power source circuit.

Figure 1. Transistor Symbol of Various Types

In general, the transistor has three terminals. Voltage or current that is installed in the terminal set larger currents through 2 other terminals. A transistor is a very important component in modern electronic world. In analog circuits, transistors are used in amplifiers (amplifier). Analog circuits surround loudspeakers, a stable power source, and a radio signal amplifier. In digital circuits, transistors are used as high-speed switches. Some transistors can also be arranged in such a way that it serves as a logic gate, memory, and other components.

Types of Transistor

A. NPN Transistor

NPN transistor consists of a p-type semiconductor layer between two layers of n-type. Small stream that enters the base on single emitter amplified in the collector output. In other words, life NPN transistor when the base voltage is higher than the emitter. The arrow in the symbol is placed on the emitter leg and points out (direction of conventional current flow when the device triggered forward).

B. PNP Transistor

PNP transistors consist of a layer of n-type semiconductor between two layers of p-type semiconductor. Small stream leaving the base on a single mode emitter amplified in the collector output. In other words, life as a base PNP transistor is lower than the emitter. Arrows on the symbol placed on the emitter and pointing into.

How its Work

Of the many types of transistors, in the beginning there are two basic types of transistors, bipolar junction transistor (BJT) or bipolar transistors and field-effect transistor (FET), which each works differently. Bipolar transistors are so named because the main conduction channel using two polarity charge carriers electrons and holes, to carry electric current. In BJT, the main electric current must pass through the area or boundary layer called the depletion zone, and the thickness of this layer can be set at high speed in order to regulate the flow of the main stream.

Field-effect transistor (FET) is also called a unipolar transistor because it uses only one type of charge carriers (electrons or holes, depending on the type FET). In the FET, the main electric current flowing in a narrow conduction channel with a depletion zone on either side (compared to the bipolar transistor in which the base area of ​​the main cutting direction of the electric current). And the thickness of the border area can be changed with the change of applied voltage, to change the thickness of the conduction channel.


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