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ADS1284: High Frequency performance at high gains

Gareth Goldswain
Prodigy 65 points

Part Number: ADS1284

Tool/software:

We use the ADS1284 in some of our products.

An end-user has stated that they have noticed an unusual drop-off in high-frequency response for higher gain levels.

I have asked the end-user for more information, and have checked the datasheet, but I see no mention of gain-dependent frequency response of this part. Is there perhaps an undocumented gain-badndwidth effect of the PGA, or something else that could explain this behaviour?

Thanks,

Gareth

  • 0
    TI__Guru 50290 points

    Hello Gareth,

    The PGA frequency response should be flat for all gains out to 1600Hz, which is the bandwidth of the FIR filter at 4ksps.  If you are bypassing the FIR and directly using the SINC filter, then you may see some attenuation at higher frequency.

    What gain and filter mode are you using in this case?

    Regards,
    Keith Nicholas
    Precision ADC Applications