It seems difficult to implement our AC coupled circuit in D1300694_v1 board which is DC coupled.

Meanwhile, I was looking into improving noise performance of present design ISS3, and it seems we can get some improvement directly by including a buffer at the input (to have good input impedance) and reduce resistance values in stage 1 to lower the impact of the current noise of first stage amplifier. This design ISS3_1 and its LISO analysis are attached.