AD5941 is Noisy in Several Freq

No. Floating pins don't affect the measurement unless you use those pins for acquisition in your code.

I am using the following switch matrix configuration:

Mux Settings: SWD_CE0 | SWD_AIN1, SWP_PL, SWN_NL, SWT_TRTIA | SWT_AIN2

FYI the noise increases also over time, even without load on the probes

Do you have any recommendations on where to look for the root cause of this noise issue?

Is that possible, that the random noise coming from the moisture sensitivity?

pre-heating before reflow the AD chip makes this issue solved (even using a previously used chip that was known to have issues). Seems like parasitic leakage (internally) that is caused by the moisture sensitivity? Since this issue always occurred at random frequencies (not at certain freq).

Kind Regards,

Specia

Could be due to moisture sensitivity, since it works fine after pre-heating.

Could be due to moisture sensitivity, since it works fine after pre-heating.