Could someone explain how/whether the input antialiasing filters on AD7606 are intended to provide complete rejection of signals above the Nyquist frequency ? Datasheet Figure 37 shows the attenuation reaches 25dB at 100KHz (half sample-rate), but I would have thought that 16-bit conversion requires 96dB. Or is it expected that the typical application for this device will have already have some inherent roll-off in the input signal ?
My application only requires 10KHz bandwidth on 3 channels, with 16-bit resolution. So the AD7606 with OS8 oversampling would be a good choice (and even gives some bonus resolution), if it doesn't require additional input filtering. Otherwise it may be that a sigma-delta device with higher oversampling would make more sense - any suggestions would be appreciated.