AnsweredAssumed Answered

AD7763 on-chip differential amplifier not providing offset?

Question asked by pmrshudson on Nov 9, 2016
Latest reply on Nov 10, 2016 by JellenieR

I am using the on-board differential amplifier on the AD7763 to provide the appropriate offset to my input signal before going to the analog to digital converter. Normally, this all works correctly. However, I have a few boards that are not providing the proper DC offset. Can anyone provide a reason why this would not be working? Here are my operating parameters:

 

Differential input signal scaled to +/ 1.024V based around ground before going to the on-board diff amp.

AVDD1 2.5V

AVDD2 5.0V

AVDD3 5.0V

AVDD4 5.0V

DVDD 2.5V

Vref 4.096V

Rbias 162kohm

 

See schematic below

Outcomes