low offset？

[mickey0908]

how to design a low offset op ? thanks

 

[melodyseu]

Big input transistor
Try auto zero or chopper technique

regards

 

[zajbanlik]

Placing bipolar transistor in diferential amplifier would be also good idea.

 

[pkalavakuru]

Hallo Hallo


Bipolar is Ok , but how to get rid of base current? Anyways it depends , if u have bicmos technology.

Generally Take mos as Diff pair and try to dimmension it , so that it has enough gm/B.W/ 1%matching error. Don't forget to concentrate on ur current load(u have to consider 1% matching error).

Most imortant thing is , how you do ur layout? Try to fetch the best one for ex: Commmoncentroind Layout technique for Diff pair layout..

There r somany other ways to remove offset , ex chopping techinue(Auto zero technique) but if u want to do with simple OPAMP. these r the parameters which u have to consider.


Best of Luck

 

[mickey0908]

thanks ! how simulator ?

 

[timo67]

The best way to design low offset Op Amps is to use the Chopper stabilized Op Amps
read:
Circuit Techniques for reduicing the effect of Op Amp Imperfections: Autozeroing, correlated double sampling, and Chopper Stabilization
C. ENZ and G. TEMES
IEEE 1996
proceedings of the IEEE VOL84 NO 11 november 1996