SARA-G3 and SARA-U2 series - System Integration Manual
UBX-13000995 - R26
Design-in
Page 155 of 217
Avoid coupling of any noisy signal to speaker lines: it is recommended to route speaker lines away from
module
VCC
supply line, any switching regulator line, RF antenna lines, digital lines and any other possible
noise source.
Avoid coupling between speaker / receiver and microphone lines.
Optimize the mechanical design of the application device, the position, orientation and mechanical fixing
(for example, using rubber gaskets) of speaker and microphone parts in order to avoid echo interference
between the downlink path and uplink path.
Route speaker signal lines as a differential pair embedded in ground up to reduce differential noise pick-up.
The balanced configuration will help reject the common mode noise.
Cross other signals lines on adjacent layers with 90° crossing.
Place the bypass capacitor for RF close to the speaker.
