Audio track and pcb layout recommendation, Figure 22, Audio track design – Sierra Wireless AIRPRIME WISMO218 User Manual
Page 56: Figure 23, Differential audio connection
WA_DEV_W218_PTS_002
Rev 006
April 29, 2010
56
Product Technical Specification &
Customer Design Guidelines
Interfaces
3.10.5.5. Audio Track and PCB Layout Recommendation
To avoid TDMA noise, it is recommended to surround the audio tracks with ground as shown in the
following figure:
Figure 22.
Audio Track Design
For differential connections, it is necessary to add a 2.2KΩ resistor from MICN to GND to have a
proper bias of the microphone. Refer to the following figure.
Figure 23.
Differential Audio Connection
For single-ended connections, the negative pole of the microphone, MICN, should be connected to
GND. Refer to the following figure.
Differential Audio line is
always in parallel