Mumbai University > Electronics Engineering > Sem 4 > Discrete Electronic Circuits

Marks: 5M

Biasing is nothing but making use of resistors and power supply connected in such a way that to obtain collector emitter voltage and collector current.

The need of providing dc biasing for transistor is to obtain a dc collector current at a certain dc collector emitter voltage.

These values of current and voltage are expressed by the term called as operating point or quiescent point.

To obtain the operating point we have to use some circuits, these circuits are called biasing circuits. So that while fixing operating point, it should provide proper dc conditions so that specific function is achieved.

Transistor operates in four different regions i.e Cutoff, Forward Active, Saturation, Inverse Active.

Requirements of biasing circuits:

Establish the operating point in the centre of load line, so that when we apply input signal the operating point does not move either in saturation or cutoff region.

Make Q-point independent of device parameters variation so that it does not shift.

Stabilize the collector current against temperature variations.