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Original question:

ADS131M08: How to know how much harmonic supported by data convertor ADS131M08 or ADS131E08

ADS131E08: SINC filter attenuation

Rajasekaran Venkidusamy
Prodigy 20 points
Part Number: ADS131E08

My interest on measuring 40th harmonics when my fundamental frequency is 60hz , what  I understood is due to SINC filter signal attenuation is high at 2.5 KHz input signal (Harmonics signal)  ,  I would like to understand the signal attenuation compensation for ADC131E08 for 40 th harmonic signal , 

  • 0
    TI__Guru 57296 points

    Hello Rajasekaran,

    Thank you for your post.

    The Sinc3 filter response in the ADS131E08 will scale with the output data rate. Generally, the data rate should be configured beyond the signal bandwidth of interest to minimize attenuation from the digital filter. As you can see in Figures 23-27, the filter response has notches at multiples of the data rate and the response repeats at multiple of the modulator frequency, fMOD. The -3-dB bandwidth of the filter is 0.262*fDR. In order to measure 40 harmonics of 60 Hz (~2400 Hz), you would require a data rate of 9.6 kHz or greater to limit the digital filter attenuation to less than -3 dB.

    Regards,

    Ryan