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Hi experts!
My customer has the following question about the ADS8688AT:
We’ve been interested in using AD8688 for some low frequency signal processing. But, we’d like to do some differencing digitally and are worried about the CMRR achievable when the AA filters in the part aren’t specified tightly. What I’m wondering is there any test data available of the statistics of the corner frequency and Q factor of the filters? They are rated nominally as 15kHz, but not with tolerance, min-max, or most useful, matching characteristics.
Can we provide any additional guidance regarding the filter or how to achieve what they're considering?
Best regards,
Jim B
Hi Jim,
ADS8688 can only support single-ended input analog signal, not differential signal, the AIN_nGND should be restricted to +/-0.3V, this is the reason why there is no CMRR spec in the datasheet. The 15kHz is the -3dB cutoff frequency of 2-order low-pass filter. What's the signal frequency in the customer's system? What's the specific reason the customer is worried about the CMRR?
Regards,
Dale