- #1
likephysics
- 640
- 4
I'm trying to understand emitter degeneration.
Instead of the entire input applied across just the VBE junction, it is now applied across the VBE junction plus an emitter resistor RE.
So when collector current increases, some additional voltage is dropped across RE, so that voltage across VBE does not increase by a lot.
Let's say Ic is 1mA, RE is 1k. Voltage across RE is 1v, VBE is 0.650v
Now Ic increases by say 10% (due to beta change or whatever), Ic=1.1mA, Voltage across RE is 1.1v, what's VBE? How do I calculate VBE.
I don't understand why it's called negative feedback.
Anything that reduces collector current is called negative feedback?
Instead of the entire input applied across just the VBE junction, it is now applied across the VBE junction plus an emitter resistor RE.
So when collector current increases, some additional voltage is dropped across RE, so that voltage across VBE does not increase by a lot.
Let's say Ic is 1mA, RE is 1k. Voltage across RE is 1v, VBE is 0.650v
Now Ic increases by say 10% (due to beta change or whatever), Ic=1.1mA, Voltage across RE is 1.1v, what's VBE? How do I calculate VBE.
I don't understand why it's called negative feedback.
Anything that reduces collector current is called negative feedback?