What is the input offset voltage of an op-amp?

Figure 1 Inverting amplifier with an input offset
Figure 1 Inverting amplifier with an input offset

In the case of the ideal op-amp, the DC voltage of the VIN(+) and VIN(-) terminals match exactly when the input voltage (Vi) is 0 V. In reality, however, there are differences in input impedance and input bias current between the VIN(+) and VIN(-) terminals, causing a slight difference in their voltages. This difference called input offset voltage is multiplied by a gain, appearing as an output voltage deviation from the ideal value.
When used in amplifiers of sensors, etc., the input offset voltage of an op-amp results in an error of sensor detection sensitivity. To keep sensing errors below a specified tolerance level, it is necessary to select an op-amp with low input offset voltage.

Figure 2 Output waveform of an inverting amplifier with an input offset
Figure 2 Output waveform of an inverting amplifier with an input offset

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