I’m working on a transimpedance op-amp design using the ADA4530-1. We have an existing electron multiplier (labeled “Detector” in the attached diagram) which produces a small current as an output signal. The detector is connected to the TIA circuit through a short length of coaxial cable. There is one common ground shared between the detector and the TIA circuit. The coax cable shield carries this ground to the TIA circuit. See the attached circuit diagram
My question is: what should I do with the GUARD pin output on the AD4530? Under the “Cables and connectors” section of the datasheet, it says to use the inner conductor for the high impedance trace, and the shield for the low impedance trace. But in my case, that would mean connecting the guard trace directly to ground. I assume my only option is to surround the signal trace on the TIA PCB with the GUARD signal, and not attach it to the coax shield?
