Conflicting recommendations for matching components

[dwanninger]

Hello,

I'm using the nRF52840 in a new design, following the reference designs as a guide.  I've noticed that the reference layout files and the development kit use a different pi network for matching the RF port.  Is one preferred, or is this just something that must be tuned once boards are built.

Here are screenshots.

nrf52840_quiaa_var5.SchDoc:

PCA10056:

[Jay Tyzzer]

Please use the reference design Schematics and Layouts. 

https://www.nordicsemi.com/-/media/Software-and-other-downloads/Reference-Layouts/nRF52840-QIAA-Reference-Layout-1_1.zip?la=en&hash=AADE4CF18BAB55788294E9CE63A4339506D29F95

https://www.nordicsemi.com/-/media/Software-and-other-downloads/Reference-Layouts/nRF52840-CKAA-Reference-Layout-1_0.zip?la=en&hash=5F4891146419E62B74A05605DC805CF596FA8532

Also note that this matching network is to match the  impedance of the ANT pin to 50 ohms. This network is different between the  QFN and the WCSP part. Also, C22  should be included in layout but no component is mounted.  An additional matching network is needed near the antenna.  The type and number of components needed will depend on the type of  Antenna used.

[Simonr]

I'd also like to add that the matching in the PCA10056 version is specifically tuned to the Dev kit antenna, and is not likely to fit just any other designs. As Jay says, please use the reference designs.

Best regards,

Simon