User's Manual

USER MANUAL

TCM 300 / TCM 300C / TCM 300U

TCM 320 / TCM 320C / TCM 320U

4.5 Power supply requirements

In order to provide a good radio performance, great attention must be paid to the power

supply and a correct layout and shielding. It is recommended to place a 22 µF ceramic ca-

pacitor between VDD and GND close to the module (material: X5R, X7R, min 6.3 V to avoid

derating effects). In addition a 470 nH coil shall be inserted (Murata LQW18A, 0603) in the

power supply line.

For best performance it is recommended to keep the ripple on the power supply rail below

10 mVpp (see 3.4).

All GND pins must be connected to GND. Be careful not to create loops! The

ground must be realized ideally on both sides of the PCB board with many Vias. At

least there must be a short star connection. Otherwise RF performance can be

reduced!

4.6 Layout recommendations

The length of lines connected to I/Os should not exceed 5 cm.

It is recommended to have a complete GND layer in the application PCB, at least

in the area below the module and directly connected components (e.g. mid-layer

of your application PCB).

Due to unisolated test points there are live signals accessible on the bottom side

of the module.

Please follow the following advices to prevent interference with your application

circuit:

 We suggest avoiding any copper structure in the area directly underneath

the module (top-layer layout of your application PCB). If this is not possible

in your design, please provide coating on top of your PCB to prevent short

circuits to the module. All bare metal surfaces including Vias have to be

covered (e.g. adequate layout of solder resist).

 It is mandatory that the area marked by the circle in the figure below is

kept clear of any conductive structures in the top layer and 0.3mm below.

Otherwise RF performance will be degraded!

 Furthermore, any distortive signals (e.g. bus signals or power lines) should

not be routed underneath the module. If such signals are present in your

design, we suggest separating them by using a ground plane between

module and these signal lines.

The RVDD line should be kept as short as possible. Please consider recommenda-

tions in section 4.10.