Considering AD7606B but need more PGA ranges (down to +-20mV)

Hi,

I'm considering an AD7606B for its channel count, oversampling capability and ease of synchronisation.

I am trying to digitise a modulated 5kHz sine wave carrier (from 4, 8 or more sources) and need to acquire 8 samples per cycle (40ksps) for a lock-in correlating demodulator. Demodulated bandwidth is about 1 to 2kHz. I intend to clock the ADC at 640kHz and use the oversampling function to achieve 40ksps. 16 bits of resolution is sufficient but 18 would be better (limited by Johnson noise).

A range of signals are to be connected, hence the need for 10V to ~20mV range. Can you suggest an appropriate additional PGA?

I also need to allow some future-proofing by perhaps increasing the data rate (by reducing the oversampling). This is a nice-to-have for product specmanship.

Is this an appropriate ADC? I have also considered AD7771 and AD7768 (and ADS8688).

FYI, I am considering using and AD9542 to derive the 640kHz clock from a distributed 5kHz system clock (covered in another post)

Am I on the right track?

Thanks in advance,

Steve



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[edited by: Lluis at 8:41 AM (GMT 0) on 20 Apr 2020]