Use the multi-layer host board for routing signals on the inner layer and the bottom layer.
The top layer (underneath the module) of the host
board must be ground with as many GND vias as possible, (see the following
figure).
Avoid fan-out of the signals under the module or
antenna area. Use a via to fan-out signals to the edge of the WBZ45 Module.
For a better GND connection to the WBZ45 Module, solder the exposed GND pads of the
WBZ45 Module on the host board.
For the module GND pad, use a GND via of a minimum 10 mil (hole diameter) for good ground to all the layers and thermal conduction path.
Adding a series resistor on the host board for
GPIOs, mainly critical high-frequency pins and clocks for EMI considerations is
recommended. The value of the series resistor depends on the actual pin
configuration. The user must place these resistors close to the module. The
following figure illustrates the placement of the series resistor.
