Merits and Demerits of Voltage divider bias:

Merits:

1. Not like the above circuits, only one dc supply is essential.

2. Operating point is approximately independent of β variation.

3. Operating point stabilized against shift in temperature.

Demerits:

In this circuit, to keep I_C independent of β the following condition must be met:

That is approximately the case if

(β + 1) R_E >> R₁ || R₂

In which R₁ || R₂ represents the equivalent resistance of R₁ and R₂ connected in parallel.

As β-value is set for a given transistor, this relation can be fulfilled either by keeping R_E fairly large, or making R₁||R₂ extremely low.

If R_E is of large value, high V_CC is essential. This get increases cost as well as precautions essential while handling.

Either R₁ is low, or R₂ is low, or both are low if R₁ || R₂ is low. A low R₁ raises V_B closer to V_C, get reducing the available swing in collector voltage, and limiting how large R_C can be made with no driving the transistor out of active mode. A low R₂ lowers V_be, reducing the permitted collector current. Lowering both of the resistor values draws much more current from the power supply and lowers the input resistance of the amplifier as observed from the base.