Analog signal chain – Two point calibration

[Alex]

Hi all

My question regarding the subjet is related to the expected error you can get after you done offset and Gain calibration.

I have a simple signal chain which include a PGA  and  16 bit DeltaSigma ADC.

I can get very close values after calibration on each end of a ADC input range: 0 mv to 512 mv.

The  corrected values after using the Corrected_Gain and offset  are not very close to ideal Gain=1.

Near Full Scale the valus are good but the error increase down to cero volts.

Ther are error like INL which is  +/- 2LSB , but the error I get is big compared to 2 LSB.

I would appreciate  any help on that.

Regards,

 

[Amerdas D K]

you must take average of several codes….more will the number of samples less will be the gain error

[Author]

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