I am currently designing an analogue front-end for strain gauges but I am a little confused with something. First of all, to explain the chain, you can have a look at the attached schematic. The instrumentation amplifier that I use is the AD623 from Analog Devices. The LPF in front of the amplifier is for suppressing RF interference and is designed as suggested at page 17 of the device's datasheet. Let us assume that the desired sampling rate from the ADC is around 2kHz. My questions are the following:
(1) Since the expected BW of the output signal from the strain gauge bridge is around 1kHz, I wonder how much should be the frequency of the RFI filter before the amplifier. I guess that the cut-off frequency should not be lower than 1kHz. But if this is the case, how can a RF signal of i.e. 50-60Hz from external power supplies can be filtered out?
(2) I am thinking of using an anti-aliasing filter between the amplifier and the ADC, in order to increase the SNR. Is this approach recommended for my case?