How to analysis offset voltage in OP-AMP?

[kankanas]

Hello all,

I need help understanding the calculation of offset voltage for OP-AMP. Currently, I am trying to find the offset voltage of TL074 in LT-Spice. As per the datasheet given, Input offset voltage (Vos) is typically 3mV and Max 10mV. (supply is +-15V)

My understanding is if we short the two inputs of the OPAMP to ground and measure the
output voltage, whatever value will get at output node is the OUTPUT offset voltage not input offset voltage. To measure input offset voltage a test voltage has to be added in one of the input terminals and have to vary. The value at which output becomes 0V must be INPUT offset voltage. But I am not sure as the input offset is not matching with the datasheet and any information about OUTPUT offset I could not see. So, My doubts are in general theoretically----

1. How to find the input offset as well as the output offset of an OP-AMP? (Please provide circuit configuration for both)

2. When the OPAMP is included in big circuit configuration how we can approach for offset voltage at each node?

3. Can the offset change with different configurations and different feedback strategies (negative feedback and open loop mainly)?

Thanks in Advance

KS

[Simon]

Please do not double post. It is annoying and will not get you help any quicker.