The input offset voltage (
An ideal op-amp amplifies the differential input; if this input is 0 volts (i.e. both inputs are at the same voltage with respect to ground), the output should be zero. However, due to manufacturing process, the differential input transistors of real op-amps may not be exactly matched. This causes the output to be zero at a non-zero value of differential input, called the input offset voltage.
Typical values for
Input bias current and input offset current also affect the net offset voltage seen for a given amplifier. The voltage offset due to these currents are separate from the input offset voltage parameter and is related to the impedance of the signal source and of the feedback and input impedance networks, such as the two resistors used in the basic inverting and non-inverting amplifier configurations. FET-input op-amps tend to have lower input bias currents than bipolar-input op-amps, and hence incur less offset of this type.