Bipolar junction transistor is a semiconductor device, which can amplify electronic signals, such as radio and television signal. It is an essential ingredient of each electronic circuit of the amplifier or the more simple oscillator to the most elaborate of the digital computer. Now tubes of the day are replaced by the transistor, and some following advantages are taken by the transistors.
It is,
1. Low operating voltage
2 Greater efficiency
3 Robustness and small size
4. It does not require any power filament
TRANSISTOR is a terminal device three, as a Base, emitter and collector. It can run by three configurations, such as the common, transmitter base joint and common collector. Depending on the configuration, that it can be used for voltage and current amplifier. The concept of transfer of resistance gave the name of transfer resistances.
There are two types of transistors, the unipolar junction transistor and the transistor bipolar junction. Unipolar transistor current conduction is only due to a type of carriers, as the majority. The current conduction in bipolar transistor is because of these two types of charge carriers are holes and electrons. Therefore, this is called transistor bipolar junction.
The bipolar junction transistor has two types,
1 Type N-p-n
2. Type P-n-p
Principle of Transistor bias:
To operate the transistor as an amplifier, it is necessary to bias properly junctions of two p - n with external tensions. According to the use of external bias voltage polarity and the transistor operates in a three regions.
1. Region active
2 Clipping region
3 Saturation region
Construction of a transistor:
The transistor can be constructed using five basic techniques and therefore they are classified as,
1 Type grown
2. Type of alloy
3 Electro etched chemically type
4. Type of dissemination
Cultivated type:
This technique is used to form the junction of two p - n junction transistor grown. A single crystal is based on a silicon or germanium magma with the impurity concentration change during Crystal drawing operation.
Type of alloy:
This type of construction is p-n-p transistor. This construction is also known as the amalgamated construction. Here, the Centre section is a thin wafer of material n. The collector is made larger than the transmitter to withstand the heavy current and dissipation of power to the base collector junction.
Type engraved electronically:
In this technique, etching of depression is made on the sides of a range of semiconductor to reduce the thickness of the base area. Electro-chemically attack chemical devices are also reference surface-barrier transistor. However, these devices are more commercially important.
Type of scattering:
Diffusion is a process by which a high concentration of particles diffuse in the surrounding region of lower concentration. The main difference between the spread and the alloy process is the fact that the liquefaction is not reach in the dissemination process. Heat is applied to the process of mailing only to increase the activity of the elements may be involved. Bipolar junction transistor
