Hello everyone!
I am working with the EVAL-ADuCM355 board to perform impedance spectroscopy. At the moment, I am able to obtain correct measurements only in a relatively narrow band around 20–30 kHz. Below this range and above it, the measured impedance appears to saturate to the value of the calibration resistor (Rcal = 200 Ω), while the DUT does not seem to be correctly resolved. In my firmware, I am using:
-HFOSC set to 32 MHz for the AFE ADCRate = ADCRATE_1P6MHZ,
-ADCSinc3Osr = ADCSINC3OSR_4,
-DFTNUM = 8192, DFTSRC = DFTSRC_SINC3, Hann window enabled
-HSTIA: RTIA = 5 kΩ, CTIA ≈ 16 pF
-AFE power mode: AD5940_AFEPwrBW(AFEPWR_HP, AFEBW_250KHZ)
Could you please advise if there are additional configuration steps or recommended settings to obtain reliable impedance measurements outside the 20-30 kHz range, especially towards higher frequencies? If useful, I can share snippets of my initialisation code. Thank you very much in advance for your support!
