AFE4300 different result with AC rectification and I/Q Modulation

Hello,

In FWR mode, only the module of the impedance can be obtained.

In I/Q mode, use equation (19) from the datasheet to compute the magnitude and phase using the I and Q data.

Both FWR and I/Q modes require different calibration procedures to compute the proportionality factor for accurate results.

An application report explaining the impedance measurement using AFE4300 is in progress and will be available by the end of February.

Can you provide details about your impedance network?

Praveen Aroul said:

An application report explaining the impedance measurement using AFE4300 is in progress and will be available by the end of February.

Can you provide details about your impedance network?

Hi Praveen Aroul, is the document available now? Where can I find it?

Hello Juan,

I have attached the document in the thread below:

http://e2e.ti.com/support/applications/high_reliability/f/30/p/256837/900130.aspx#900130

Let me know if you have issues accessing the document.

Ok Praveen, I've downloaded the document, thank you so much!

Hi again Paveen.

I have a doubt regarding with the electrodes, It came from watching some comercial scales which I will use as reference for my design, I noticed that they dont use a conductive material to make the electrodes when measuring the bioimpedance. Could I use capacitive electrodes with the AFE4300? In a negative case, could you point me to the suggested electrode design (material, dimensions, etc)?

Regards,

Juan S. Morant P.

Hello Juan,

The current signal that is injected and the voltage signal that is measured are AC. Also the transmit and receive circuits are locally biased.

So theoretically it should work. But we have not tested with capacitive electrodes.

Can you tell me more about the electrodes from the commercial scales? Are those ITO electrodes?