Migrating nRF52832 layout from QFN to WLCSP

[ricsilvs]

When designing the layout for my circuit using nRF52832 I've noticed that the values of CL connected to the ANT pin changed from L= 3.9nH and C=0.8pF to L=3.3nH and C=1pF.

The value of the capacitor connected to DEC2 also changed from an open circuit (N.C.) to 100pF.

What are the reasons behind these changes?

[FormerMember]

L, C and the traces connected to those components form a filter to filter out harmonics. I guess that during measurements it was found that slightly different filters was needed for QFN and WLCSP. In addition to component values, it is important that the traces from the nRF52 to C/gnd and L have the same length as in the reference layout.

On the QFN package, having a capacitor on DEC2 will reduce the RX performance.