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AD5941 optimising for low frequency Impedance measurements

Category: Software
Product Number: AD5941
Software Version: master

I have been running some experiments to compare the AD5941 development board to a PalmSens4 potentiostat for EIS applications.

The AD5941 is running the stock impedance example code and performing a frequency sweep between 1 and 10kHz. We get really promising results in the 300-10,000 Hz range However we struggle to get good data at lower frequencies.

For these experiments a Randals circuit with a 560 Ohm  resistor connected in series to (10 K ohm in parallel with 33nF capacitor) is used as the load. 

Viewing the raw data we can see that both the phase and impedance measurements appear noisy/unstable at the lower frequency range. 

Is there any advice on how to modify the Impedance example code to better perform at lower frequencies? I noticed that when taking measurements with the PalmSens lower frequencies took significantly longer to produce a valid reading. Whereas the AD5941 Impedance example has a fixed length no matter the frequency. So maybe it needs a wider sample window?

Any advice would be appreciated,