Dear Sirs, I want to use Your lmp91200 part to read isfet based ph sensor output voltage. I found out from Your datasheet and reference design it is foreseen for two electrode glass pH meters with guard. Isfet based ph meter is 3 electrode one composed of drain, source and gate electrodes. Usual circuit topology for isftet biasing and readback is based on two opa amps, one for biasing drain, one for biasing source and feedback output voltage to the gate so called cccv topology. I have doubts if I can connect my 3rd source electrode just to ground or guard inputs.