ADC questions for ultrasonic sampling, specifically AD4010

Hi there,

I am currently working on a project that requires sampling from a MEMs microphone at 500ksps at 16-bits, with the goal of recording ultrasonic sounds from bats.

After much research I believe the AD4010 would suit, but I have a few questions.

  1. In regards to the input, the MEMs microphone I will be using is analogue, and has an internal pre-amp, this means the output impedance is 400 ohms - would this be sufficient to drive the input to the ADC, or do I still need a buffer/driver?
  2. Is a digital decimation filter necessary on the output, or can I do this using a DSP?
  3. Would the AD4010 be suitable for ADC conversion for extended periods (a few minutes at a time)?
  4. And do you have any suggestions on a design for an anti-aliasing filter with programmable cutoff frequency?

Thank you for your time!

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  • 0
    •  Analog Employees 
    •  Super User 
    on Mar 21, 2019 2:58 AM

    nicstarke,

    First of all your project sounds really cool!!!! Do let us know how it works and what your experience was like using this product family.

    #1 Drive

    If you only require 500 KSPS and 16-bits you may want to try the AD4008 which is pin compatible with the AD4010.  Either way, where your signal content could potentially contain frequencies >100 KHz I would recommend a buffer such as the ADA4807-1 as the effectiveness of the High-Z mode rolls off above that frequency.

    #2 Digital Filtering

    Digital decimation can easily be done in your DSP to reduce noise in your system.   Of course be careful to filter any out of band content prior to data conversion to avoid aliasing it back into your band of interest.

    #3 Continuous Conversion.

    There is no limit to how long the part can be operated, nor is there a maximum limit to the time between conversions.

    #4 Other suggestions

    Not really sure why you would want a programmable anti-alias corner.  If you are instead looking to create a band-pass filter to increase the selectivity of the system to a particular frequency band, I would simply set the AAF appropriately to match your final conversion rate and then implement all the smarts from a filtering perspective in the digital post processing.

    Sean

Reply
  • 0
    •  Analog Employees 
    •  Super User 
    on Mar 21, 2019 2:58 AM

    nicstarke,

    First of all your project sounds really cool!!!! Do let us know how it works and what your experience was like using this product family.

    #1 Drive

    If you only require 500 KSPS and 16-bits you may want to try the AD4008 which is pin compatible with the AD4010.  Either way, where your signal content could potentially contain frequencies >100 KHz I would recommend a buffer such as the ADA4807-1 as the effectiveness of the High-Z mode rolls off above that frequency.

    #2 Digital Filtering

    Digital decimation can easily be done in your DSP to reduce noise in your system.   Of course be careful to filter any out of band content prior to data conversion to avoid aliasing it back into your band of interest.

    #3 Continuous Conversion.

    There is no limit to how long the part can be operated, nor is there a maximum limit to the time between conversions.

    #4 Other suggestions

    Not really sure why you would want a programmable anti-alias corner.  If you are instead looking to create a band-pass filter to increase the selectivity of the system to a particular frequency band, I would simply set the AAF appropriately to match your final conversion rate and then implement all the smarts from a filtering perspective in the digital post processing.

    Sean

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