Opamp offset voltage Compensation

[dhgac_296796]

Has anybody tried to null the offset voltage of PGA in PSoC5 LP? I am working with very small signal and need to take care of PGA offset voltage. I tried to check offset voltage,.. which comes in the range of 9-12 mV for PGA (Attached project )

   

Please share the compensation circuit if anybody is having tried it. 

   

Thanks in Advance!!

[EvPa_264126 · Accepted solution]

It seems you need to use ADC_SetOffset () and, if desired, ADC_SetScaledGain ()
Slightly theory:
AN68403 PSoC3 and PSoC 5LP Analog Signal Chain Calibration
It remains unaccounted for:
Input offset voltage PGA = ±30 μV/°C * gain

[odissey1]

        dhans, Technically, "0 V" voltage does not exist in PSoC, which is powered by single polarity power supply. In such mode analog "zero" is typically a Vref voltage (1.024V or Vdda/2). One way to deal with small voltages is to construct InstAmp from OpAmps and PGAs (several examples can be found on this forum). https://www.element14.com/community/community/designcenter/psoc4_pioneer_kit/blog/2014/02/12/use-a-l... Another approach is to compensate for drift and offset is to switch polarity of the signal using Mux and use consecutive measurements to remove offset in code http://www.electronicdesign.com/analog/offset-compensation-technique-improves-bridge-configured-sens... Offset compensation for AC amplifier: http://www.cypress.com/file/70971   

[dhgac_296796]

Thanks Pavloven and Odissey1 for the information. Its really useful.