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Differential amplifier filtering and antialiasing

Category: Hardware
Product Number: LTC1992
Software Version: NA


I'm working on a differential amplifier whose purpose is to condition a differential signal to be sent on a differential ADC and I'm looking for best practice advice. 

I tried to limit the bandwidth of the signal using only the anti aliasing filter but I think this is not the best because : 

1) The antialiasing filter BW is so low that the minimum acqusition time imposed by it is higher than what is possible

2) The amplifier input may be subject to some RFI

My idea is to filter the input to the previous bandwidth of the anti-aliasing filter and using a relaxed anti aliasing filter that will limit the noise bandwidth of the amplifier.

The concept is shown here below.

The amplifier reduces the signal to get into the range of the ADC and I added a series resistor followed by a capacitor to get the desired filtering, (I tried C1 between + and - inputs but I had a really bad AC behaviour). The anti aliasing filter isn't shown here

Is this a good approach or is there good practices I'm not aware of ?

Best regards,