Op Amps and Saturation

Op-Amps and Saturation

The Inverting Mode Op-Amp Rf R1 +

V1

+Vs

-Vs

Vo

0V

In theory, the gain of the op-amp is given by Rf ÷ R1. This equation works well until the output voltage increases too much. We must remember that the op-amp has a power supply.

By increasing the input voltage, we find that the output voltage is limited. The op-amp cannot give out any more than about 85% of the voltage it is being supplied with (±15 V). We say that the op-amp saturates.

Op-amp is saturated

The gain equation works well on this part of the graph.

Op-amp is saturated

Saturation • The op-amp will saturate if the input voltage is increased too much or if the gain is increased too much.