PCB layout
RF circuits operating at high frequencies are normally sensitive to the physical layout of the
PCB. Chipcon has carefully optimized the layout of the CC2420DB Demonstration Board and
we therefore recommend that our customer copy, at least the RF parts and the decoupling
around the CC2420 when making their own PCB designs.
The PCB is of a 4-layer type in order to provide a well-defined ground plane as well as
adequate routing space. The laminate used is standard FR-4 board material. The PCB is
1.0mm thick, with layer 1 on the topside, layers 2 and 3 are internal layers and layer 4 is on
the bottom side. Layers 1 and 4 are used for routing, while layer 2 is a ground plane and layer
3 is used for power routing. All areas in the RF section that are not utilized for routing are
filled with copper connected to ground to provide RF shielding. The ground planes on all
layers are stitched together with closely spaced vias. Please see figure 8 for a board stack up
for the CC2420DB PCB.
Figure 8: CC2420DB Layer Build Up
Chipcon AS
SmartRF
®
CC2420DBK Demonstration Board Kit User Manual
(rev. 1.3) 2004-11-03 Page 16/ 52
