Consulting a question about ADA4254

Hi,

Until you get the answer from ADI, I think the PGIA might not be biased properly. I do not know this part, but your figure shows that although the IA inputs are shorted, none of the inputs are biased, in which case a typical IA won't work properly. See for example the application note 'If All Else Fails, Read This Article. Avoid Common Problems When Designing Amplifier Circuits' (https://www.analog.com/en/resources/analog-dialogue/articles/common-problems-when-designing-amplifier-circuits.html). Fig.4. shows a very similar case. Fig.5. and Fig.6. show solutions.

Zoltan

Hi jerrytang ,

Good day. I agree with Zoltan. The PGIA input is not properly biased if you only closed D12. The amplifier is in the non-linear region and it will not work properly and there's no guarantee on the output of IA. Thank you.

Regards,
Gilbeys

Hi jerrytang ,

Good day. I agree with Zoltan. The PGIA input is not properly biased if you only closed D12. The amplifier is in the non-linear region and it will not work properly and there's no guarantee on the output of IA. Thank you.

Regards,
Gilbeys