OPA391: Question about Discrete Electrochemical Signal Chain

Hi Juan,

Juan Ortega said:

Do you have more documentation about the values of the resistors and capacitors that are needed for this design?

LMP91000 AFE is the 3-electrochemical cell IC. LMP7721 and other low Ib precision op amps can be configured as discrete electrochemical cell (including gas cell) for the same application. 

https://www.ti.com/lit/an/snoa529a/snoa529a.pdf?ts=1723049776620

Our low Ib precision op amps may be LMP7721, OPA391, OPA928 etc., see the list below. 

https://www.ti.com/amplifier-circuit/op-amps/precision/products.html#3247max=0.02%3B1&sort=3247max;asc&

Juan Ortega said:

Do you have more documentation about the values of the resistors and capacitors that are needed for this design?

The values of Rf and Cf are bandwidth limiting filter, shown in the image below. In OPA391's datasheet, Figure 7-1 has the correct configuration. I do not know where your Figure 2 is obtained (if it is TI's reference, please let me know the link), but it is incorrectly configured. 

If you are chemical/electrical engineers, the following video series are helpful. The best way is to simulate the scenario. If you need assistant, please let me know. 

https://www.ti.com/video/series/precision-labs/ti-precision-labs-op-amps.html

https://www.youtube.com/watch?v=xYTHVYNin9Y

Best,

Raymond

Okay, thank you for your answer.
What about those components on the other side of the circuit? That part is the most unclear to me

Thank you very much for your response.

And what about using the LMP91000 AFE? It should replace what I would like to achieve using the opamps, right?