Operational Amplifiers - Technical MCQs

Q1:

fbq18_1012.gifThe input impedance is ______ for the amplifier in the given circuit. The data sheet values are Zin = 3 Momega.gif, Zout = 80 omega.gif, and Aol = 250,000.

A 4.7 komega.gif

B 22.7 komega.gif

C 3 Momega.gif

D 68.6 komega.gif

ANS:A - 4.7 komega.gif

The differential input impedance of the operational amplifier is defined as the impedance between its two inputs; the common-mode input impedance is the impedance from each input to ground. (from wiki)