Influence of the Input Offset Voltage of Operational Amplifier

The input offset voltage (VIO) is an internally generated voltage and may be considered as a voltage inserted between the two inputs (see Figure 2-6). In addition, it is a differential input voltage resulting from the mismatch of the operational amplifier input stages.

The effect on currents I1 and 12 can be determined by the following equations:

If the input voltage (VI) is zero, the equation is as follows:

Figure 2-6. Influence of Input Offset Voltage

The output voltage is the output offset voltage (VOO). The following equation can be used to determine VOO:

The value of the input offset voltage can be found by dividing the output offset voltage by the closed-loop gain.