2.3 Inverting Amplifier

An inverting amplifier is a configuration of the operational amplifier that inverts and scales the output.

Figure 2-3. Inverting Amplifier Schematic

However, due to the resistor feedback used with this configuration, the impedance of the input signal will affect the gain of this circuit; this can be seen by adding the signal impedance to R2 in the output formula. Additionally, since the embedded operational amplifiers are single supply, the non-inverting input of the operational amplifier must be biased to ensure the signal remains within the output range of the operational amplifier.

The output of this circuit can be calculated using the following formula:

V O U T ⁢ =   ( 1 + R 2 R 1 ) * V B I A S − ( R 2 R 1 ) * V I N
Warning: Never apply an input signal that exceeds the absolute maximum ratings of the device. Output signals with a predicted output above or below the absolute maximum ratings are self-limiting to the maximum or minimum values of the output range.