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ADS1274: ADS1274: Data Rate and Anti-Alasing Frequency

Reid Dorrance
Prodigy 60 points
Part Number: ADS1274
Other Parts Discussed in Thread: ADS127L01

Hello,

We are looking to implement an ADS1274 as an anti aliasing filter with at least 60 dB of attenuation for input frequencies at half the ADC's sampling rate. Is this achievable with this particular chip without any extra external filtering? The datasheet shows (Figure 60) that at around 0.5 the normalized input frequency (fin/fdata) there is about 5 to 7 dB of attenuation. Is it possible decrease the stopband frequency of the ADS1274 without slowing down the output data rate?

Thanks,

Reid

  • 0
    TI__Guru 66876 points

    Hello Reid,

    Thanks for your post and welcome to our forum!

    The frequency response of the digital filter in the ADS1274 is fixed depending on the MODE setting (High-Resolution Mode uses a slightly different filter than the other 3). In any case, the transition between the passband and the stopband will overlap 0.5 * fDATA and will not reach your target attenuation level.

    You might consider the ADS127L01 for this application. One of the wideband filter options (Wideband 2) begins to roll-off at 0.4 * fDATA and reaches the full stopband attenuation level (-116 dB) at 0.5 * fDATA. See Figures 71 and 72 below. This device is the latest single-channel, wide bandwidth ADC from the ADS127x portfolio with improved performance and decreased power consumption. These devices can daisy-chained for higher channel count systems.

    Best Regards,