Microphone Interfaces Design - Quectel M85 Hardware Design

from audio interface and audio alignment. Power alignment and audio alignment should not be parallel,
and power alignment should be far away from audio alignment.
The differential audio traces have to be placed according to the differential signal layout rule.

3.8.2. Microphone Interfaces Design

AIN1 and AIN2 channels come with internal bias supply for external electret microphone. A reference
circuit is shown in the following figure.
Module
MICxP
MICxN
M85_Hardware_Design
Differential layout
Figure 27: Reference Design for AIN1&AIN2
Confidential / Released
Close to Microphone
GND
10pF 33pF
0603 0603
10pF 33pF
0603 0603
10pF 33pF
0603 0603
GND
GSM/GPRS Module
M85 Hardware Design
ESD
Electret
Microphone
ESD
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