• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 46 subscribers
  • Views 549 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

AFE4300 selecting BIA frequencies and measuring R/Xc resistance/reactance of the impedance magnitude

Yuriy Chesnokov
Prodigy 30 points
Other Parts Discussed in Thread: AFE4300

Dear Sirs

Is it possible and how to obtain resistance R and reactance Xc values of the measured impedance Z in AC mode and I/Q demodulation mode? Z = sqrt(R^2 + Xc^2)

What frequencies are supported in AC mode and I/Q mode and how to set them in the device? I'm confused if the only choice is restricted to 8, 16, 32 and 64 kHz

Yuriy

  • 0
    TI__Mastermind 18285 points

    Yuriy,

    In the GUI you will see in the lower right hand corner how to set this frequency. In I/Q mode you are limited to the selected frequencies, but in FWR mode you are not.


    Also for your reference I have included a link to our AFE4300 FAQ.

    https://e2e.ti.com/support/applications/high_reliability/f/30/t/370709

  • 0 in reply to Amy Schnoor
    Prodigy 30 points
    Dear Amy

    Thank you very much for you quick reply!

    Is my understanding correct that in I/Q mode due to IQ_DEMOD_CLK = fCLK / (IQ_DEMOD_CLK_DIV_FAC) = BCM_DAC_FREQ × 4 restrictions the set of frequencies is limited to 8, 16, 32, 64, 128, 256 kHz?

    Why such set of frequencies is used? Typically in MF-BIA or in BIS 1, 50 and 100kHz are used as reported in all research papers.
    Is it possible to measure impedance at those frequencies with your device in a single measurement?

    Would you be able to confirm that the device is only measuring impedance magnitude Z which is square root of the sum of resistance and reactance squared sqrt(R^2 + Xc^2) and it is not possible to measure R and Xc directly?

    Yuriy
  • 0 in reply to Amy Schnoor
    Prodigy 30 points
    Dear Amy

    From the www.ti.com/.../technicaldocuments link there is external article "Minimal implementation of an AFE4300-based spectrometer for electrical impedance spectroscopy measurements" iopscience.iop.org/.../012014 which states:

    "The standard errors (SE) of the Cole model parameters were estimated from the fitting in figure 3 (B) − (C)"

    which displays Cole-Cole plot of the R resistance vs -Xc reactance

    "The frequency sweep electrical impedance spectroscopy measurement performed is measured at 18 frequencies within the range 2 kHz → 100 kHz (see an example in figure 3 (C))."

    suggests exceeding the predefined (8, 16, 32, 64kHz) limitations in I/Q mode

    Would you be able to help me in resolving these issues?

    Yuriy