Can anyone tel what is function of RC in the above figure.
AMP01 gain is 20 Rs/Rg, so at low frequencies the capacitor will look like an open circuit thus giving you a gain of 20. While at high frequencies it will be short circuit and that gives you a gain of ~500. The RC circuit will provide some rejection of dc offsets and low frequency noise for an ac measurement.
By the way, may I know your application? Thanks.