1.

What is the input impedance of the following CG stage?(a) 1/gm(b) 2* Rs || 1/gm(c) Rs || 1/gm(d) Rs || 2/gmThis question was posed to me in an interview for job.This question is from MOSFET Amplifier with CG Configuration in chapter FET Amplifiers of Analog Circuits

Answer»

Correct answer is (c) Rs || 1/gm

For explanation: The input IMPEDANCE can be calculated by performing a SMALL SIGNAL analysis at the input node. We need to set Vg and Vdd to 0V and apply a small input voltage at the source. Now, the impedance looking into the source is 1/gm and Rs is parallel to this impedance. Hence, the TOTAL input impedance is Rs || 1/gm.



Discussion

No Comment Found

Related InterviewSolutions