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Ultrasonic sampling ADC questions.

Other Parts Discussed in Thread: ADS8685, ADS8883

Hi there,

I am working on a project that requires sampling from a microphone at upwards 500ksps, but I am a bit confused as to the best type of ADC.

I am looking for single ended or pseudo-differential input, 16-bit resolution, with minimum of 380ksps. I am also aiming for ultra-low power consumption.

I will be using this for audio recording and spectral analysis of animals (including bats).

Will an SAR based ADC give me good enough quality or will I need to stick with delta-sigma?

Thanks for your help!

  • Hi Nic,

    Welcome to our e2e forum! We have both SAR and Delta Sigma products that can reach the 16-bit/380ksps (or higher) sampling rate you are looking for. In the end, it basically comes down to system sampling dynamics. There will be a little more latency perhaps with the Delta-Sigma approach, but power consumption and other factors start to play into the final decision as well. SAR devices can sample at high speeds and reduce power consumption while in an inactive state (sampling bats during the day for instance) while Delta-sigma device may offer higher performance, they don't often scale power in quite the same way. Is safe to assume this to be a battery powered application?

  • The device is intended for battery power. I would like to use a SAR based ADC due to the power reduction, but I am concerned that there may be degradation of audio quality as it doesn't seem that they are designed for audio use. Ideally the frequency response needs to be flat between 100Hz - 200kHz. So far I've found the Texas Instruments ADS8685.
  • Hi Nic,

    The ADS8685 is a nice part, but - there is a PGA on the input that limits the bandwidth to about 15kHz. The devices that we have which are specifically designed for audio, don't usually work well outside the human auditory range. The ADS8883 might be a better choice for your application. Its got good AC specs and the power scales directly with the sample rate.