Sorry Sunny I didn't make a screenshot of the 82pF proximitiy data and allready changed the filter capacitor.
A collegae suggested to keep the capacitive reactance the same as the original TI PCB coil.
Xc = 1/(2*pi*Fres*C) ==> 1/(2*pi*3.6MHz*100pF) = 1/(2*pi*0.6MHz*C) ==> C = 600pF
I added a 560pF capacitor to the LC tank instead of the 112pF. This showed instantly less noise on the proximity data output. After checking CFB I ended up with a 220pF filter capacitor.
Seemed ok, but when the target was at minimum distance this showed noise. On all other positions there was none.
RpMAX 27.704
RpMIN 3.078
1V peak-to-peak on CFB
Noise disappears when I lower RpMIN one step to 2.394 (only change I've made) but then the peak-to-peak value on CFB changes to 1.6V.
A filter capacitor of 330pF shows no noise at all but has a peak-to-peak off 0.7V.
During these last experiments inductance finally showed a value that's somewhere near the values I've calculated and measured with other equipment. On top off that: all the status boxes in the TI software are green, that's a first!