**Two Supply Emitter Bias Circuit:**

From the stability point of view, this two supply emitter bias circuit is the best of all already discussed circuits, but it has one drawback that it requires two power supplies or batteries or it requires one-split supply (dc power supply with a central point available).

Applying Kirchhoff’s second law around the circuit loop starting from V_{EE} and containing R_{E} and R_{B}

and I_{C} â‰ˆ I_{E} for most practical purposes

The above equation provides almost an exact expression for I_{E}. It can further be simplified by realizing that in most of the cases V_{BE} is negligible in comparison to V_{EE}. Also R_{B} is chosen quite small so that R_{B}/Î² is also negligible in comparison to R_{E}

So

The above equation may be used to calculate the value of I_{E} for rough calculations at first instance but for exact value of I_{E} the former expression be used.

The approximate expression for I_{E} also suggests that all the V_{EE }supply is dropped across emitter resistance R_{E}. Therefore, the emitter terminal E is at ground potential for all practical purposes.

The collector-to-emitter voltage, V_{CE} is given as

since emitter is practically at ground potential.

Thus point Q is established.

From the expression,

we see that emitter or collector current is independent of variation of temperature as Î² and V_{BE} do not appear in the said expression.

For this two supply emitter bias circuit stability factor is given as