The input impedance of a diff amp is
A) half as high as a single common-emitter stage.
B) twice as high as a single common-emitter stage.
C) the same as a single common-emitter stage.
D) four times as high as a single common-emitter stage.

Question

Quizplus · Accepted Answer

The input impedance of a differential amplifier is twice as high as that of a single common-emitter stage because the input is applied differentially across two transistors, effectively doubling the input impedance seen by the source.

The Input Impedance of a Diff Amp Is