Advantages of fixed bias of transistor in English

 NEED FOR TRANSISTOR BIASING

The amplifiers which are used to magnify the weak signal without change in its waveshape and frequency are called faithful amplifiers. For faithful amplification, the transistor amplifier must satisfy three basic conditions. They are namely: (i) proper zero signal collector current (ii) proper base to emitter voltage at any instant, and (iii) proper collector to emitter voltage at any instant. The technique of transistor biasing is used to fulfill the above said three conditions.

The proper flow of zero signal collector current and the maintenance of proper collector-emitter voltage during the passage of signal is known as transistor biasing.

The basic purpose of transistor biasing is to keep the base-emitter junction properly forward biased and collector-emitter junction properly reverses biased during the application of signals. That means the transistor must operate only inactive region. This can be achieved by using a bias battery or resistor circuit with the transistor. The resistor method is more efficient and is frequently used. The circuit used for proper biasing of the transistor is called biasing circuit. 'This circuit is used to fix the operating point at a particular level for satisfying the above said basic conditions.

TRANSISTOR BIASING

In the interest of simplicity and economy, it is desirable that the transistor circuit should have a single source of supply - thë one in the output circuit (supply voltage Vcc). The following are the most commonly used methods of biasing circuits.

i)Fixed bias

(ii) Collector to base bias

(iii) Self-bias 

ADVANTAGES AND DISADVANTAGES OF FIXED BIAS

Advantages

(i) Simplicity

(ii) Less number of components (iii) No loading of the source by biasing circuit (iv) Easily set the biasing conditions.

Disadvantages

(i) Poor stabilization

(ii) Stability factor is very high. Therefore, there are strong chances of thermal runaway.

ADVANTAGES AND DISADVANTAGES OF COLLECTOR TO BASE BIAS

Advantages

(i) Simple circuit

(ii) High stability compared with fixed bias Disadvantages

Disadvantages

(i) The circuit provides negative feedback, which reduces the gain of the amplifier.