Emitter resistance

Kermit2

Joined Feb 5, 2010
4,163
If you want to avoid using a bypass cap on the emitter resistor and AC is being amplified, then its magnitude should be considered in the selection of the resistance.

Is this a class A, single transistor, common emitter amplifier?
 

ian field

Joined Oct 27, 2012
6,539
Is it right to calculate the emitter resistance using the ac applied voltage ?
If you mean the emitter resistor in the basic common emitter stage - it basically sets the collector current.

Your base bias divider is basically Vref in the textbook single transistor current source. Subtract Vbe from the bias and the remainder is developed across Re. That sets the constant current value which is available at the collector.
 
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