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ADS1299: How to calculate the Electrode impedance of the input channels?

Part Number: ADS1299

How to calculate the Electrode impedance of the input channels? \

I found the related words but how to do it in details?

Can I ask for some help ?

  • Hello,

    Welcome to our forum!

    Electrode impedance is calculated by injecting a known excitation current and measuring the differential voltage across the electrodes. However, the current sources in the ADS1299 are not intended for impedance measurement as they are not especially accurate (typical +/-20% tolerance). The intention of providing these lead-off current sources is to give you an indication of when the contact impedance has changed beyond what you consider "acceptable," indicating poor contact quality and signaling to the user that the electrode connection should be checked. This detection can either be done in time or frequency domain by analyzing the magnitude of the signal present at the lead-off current frequency.

    Best Regards,