How to measure offset and how to reduce it

[yekmosafer]

how to measure offset

Can any body suggest me how to measure offset for an opamp (like 741) in PSpice.
And how it could be reduced. for example putting R instead of active load is helpful?
tanks!

 

[TekUT]

May be can help:

**broken link removed**
http://www.ecircuitcenter.com/Circuits/op_voff/op_voff.htm
http://www.wipo.int/pctdb/images4/PCT-PAGES/1991/061991/91003100/91003100.pdf
http://metrology.hut.fi/courses/s108-180/Luento4/chopamp.pdf

Bye
Powermos

 

[LvW]

Can any body suggest me how to measure offset for an opamp (like 741) in PSpice.
And how it could be reduced. for example putting R instead of active load is helpful?
tanks!

Offset simulation should be in accordance with its definition:
Apply a small dc voltage at one input (ground the other one) and find the value for which the output dc voltage is zero. Thereby, you plot the classical dc transfer curve.
It cannot be reduced since it is the property of the IC itself.

 

[absjoshi]

Are you talking about input offset or output offset?
Secondly if you are talking about reducing offset of a discrete IC, then it is not possible, but if you want to reduce your offset of an op amp at design level, then surely there are design techniques to do that.
and lastly if your op amp has dual supply, then above definition is correct. Incase of the single supply opamps, you need to connect the one input to common mode level instead of gnd and measure the offset from the clssical dc characteristic curve.