LTE Standard Module Series
EG915U_Series_Hardware_Design 39 / 81
as possible, and the traces should be as short as possible. They should go through the filter capacitors
before arriving at other connection points.
To reduce radio or other signal interference, RF antennas should be placed away from audio interfaces
and audio traces. Power traces should not be parallel with and also should be far away from the audio
traces.
The differential audio traces must be routed according to the differential signal layout rule.
4.1.2. Microphone Interface Design
The microphone channel reference circuit is shown in the following figure.
MIC_P
Differential
layout
Module
10 pF
33 pF
33 pF
33 pF
Electret
Microphone
10 pF
10 pF
TVS
TVS
Close to Module
MIC_N
MIC_BI AS
Close to
Microphone
2. 2uF
100nF
1K
0R
0R
100nF
1K
510R
510R
1. 5K
1. 5K
Figure 16: Reference Design for Microphone Interface
MIC channel is sensitive to ESD, so it is not recommended to remove the ESD components used for
protecting the MIC.
4.1.3. Receiver Interface Design
The receiver channel reference circuit is shown in the following figure:
NOTE