An instrumentation amp with one open input:
A) may work correctly in a low noise environment.
B) will not work at all.
C) will allow common-mode noise to be present on the output.
D) both A and C

Question

Quizplus · Accepted Answer

An instrumentation amplifier with one open input will allow common-mode noise to be present on the output. This is because the input impedance of the open input is infinite, so any common-mode voltage that is present will not be rejected by the amplifier. Therefore, option C is the correct choice. Option A is incorrect because while the amplifier may work correctly in a low noise environment, it will still allow common-mode noise to be present on the output. Option B is also incorrect because the amplifier will still function with two inputs, but it will not reject any common-mode noise that may be present.

An Instrumentation Amp with One Open Input