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AFE4300: 8.1.2 Handling Oscillation of the Excitation Amplifier

Sundar Krishnaraj
Prodigy 140 points
Part Number: AFE4300

In AFE4300 datasheet section 8.1.2 Handling Oscillation of the Excitation Amplifier.  I see a recommendation to use series Rcm, Ccm (1K, 1nF) on one of the RPx pins to prevent oscillations. However this will also have the calibration resistor connected between RPx & RNx.  Wont this affect the calibration slope & offset value ?

Suppose i have a 1 Kohm between RP1 & RN1 for calibration and also Rcm series Ccm on RP1 pin what should be the resistance value i should use in the software for the slope formula ?  Eq 1 sbaa202

thx

sundar

  • 0
    TI__Genius 12555 points
    Hi Sundar,

    Putting Rcm and Ccm will change the slope . However you can find the new slope using two calibration resistor as Rcm/Ccm will be present in all the measurement ( i.e. calibration resistor, body impedance measurement). The main objective of having a calibration routine is to find the unknown variables (i.e. slope and offset). So as long as you have Rcm/Ccm in all the measurement , the slope calculated from the calibration can be used while estimating body impedance.
    You can still use 1Kohm as one of the calibration resistor,also you need one more calibration resistor.

    Regards,
    Prabin