Op-Amp Offset Voltage Vos

If the + and - inputs are shorted together, a real op-amp does not have 0V at the output. This occurs because each half of the input differential pair is not perfectly matched.

Vo=A*Vos , A is open loop gain

Vos can be modeled as a voltage source attached to the + terminal of an ideal op-amp.

Temperature effects:

Vos is affected by temperature and the temperature drift of Vos (dVos/dTemp) is on the spec-sheet.