Question

If the output voltage is sensed at the collector, which of the following option perfectly describes the stage shown below?

(a) A degenerated C.S. stage

(b) A C.S. stage

(c) A shunted C.S. stage

(d) An open C.S. stage

The question was asked in examination.

Question is taken from MOSFET Amplifier with CS Configuration in section FET Amplifiers of Analog Circuits

Answer 1

Correct answer is (a) A degenerated C.S. stage

The best I can explain: The above shown stage is a degenerated CS stage. This stage is called so because the current source connected at the source of M1 reduces the total gain of the CS stage. The current source provides a finite output impedance which is connected the source. Thereby, the overall gain decreases.