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ADS1298: Benchmarking sensetivity

mohsen fatoorechi
Prodigy 60 points

Part Number: ADS1298

Hi,

I am using ADS1298 in my product. I can calculate a sensitivity value based on the information in the datasheet. However, I would like to measure/benchmark this figure. Do you have a standard method for doing this? how would you go about measuring accuracy of any ADC. Considering these chips can measure down to few uV it is not very straight forward to plug in a signal gen to the inputs.

Would high ratios of voltage divider help to generate a low noise low voltage signal in uV range to feed into the ADC?

Wouldn't Johnson noise stop one from using high value resister in this case?

  • 0
    TI__Guru 69446 points

    Hi Mohsen,

    Welcome to our forum and thank you for your post!

    The sensitivity of any ADC is limited by it's input-referred noise specification. This is typically measured by shorting the inputs of a given ADC channel and analyzing the distribution of digital output codes. The peak-to-peak and RMS noise measurement results are provided in the device datasheet for all combinations of gain and data rate.

    As you mentioned, using large resistors or an external signal source may introduce more noise above the noise floor of the ADC itself. It's generally desired to keep the noise from your source below the ADC noise floor so as not to limit the dynamic range of the system (difference between smallest and largest measurable signals); however, at the end of the day, what really matters is that you have enough dynamic range to measure the signals expected in your application.

    Best regards,

  • 0 in reply to Ryan Andrews
    Prodigy 60 points
    Are the noise measurement results in the device datasheet measured based on the same approach of shorting the input and analyzing the output codes?
  • 0 in reply to mohsen fatoorechi
    TI__Guru 69446 points

    Hi Mohsen - yes, we use the internal-short MUX setting to measure the noise on each channel.

    Regards,