I was studying the topology of CS amplifier with degeneration (a resistor connected from source to ground and I have two question about this topology:
- It is clear for me that Rs will decrease the gain (cons.) and increase the output resistance (cons.).
I know also that the input capacitance will decrease (pros.). Is there any other motivation behind using this series resistor Rs?
- They also mention that Rs adds noise, while adding an inductor instead will not add noise and will give the same (pros.) as the resistor. I know that resistors give thermal noise, but why inductors don't? Is it because they don't dissipate real power? And is this the only difference between adding an L or an R?