GSM/GPRS Modules
GSM Module Audio Design Guide
GSM Module Audo Design Guide Confidential/Release
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2.1. Audio Circuit Reference
2.1.1. M1x
2.1.1.1. Microphone Reference Circuit
M1x module provides electrets-microphone bias voltage for AIN1 and AIN2. Microphone reference circuit
is shown as below:
10pF
33pF
33pF
33pF
Close to Microphone
MICxP
MICxN
Differential layout
Electret
Microphone
GND
GND
10pF
10pF
ESD
ESD
Module
Figure 1
：
Microphone Reference Circuit for AIN1&AIN2
1. To avoid TDD noise issue during voice, capacitors is recommended to add close to microphone and
SPK.
2. TVS components are used to protect microphone and receiver from ESD damage. It has to close to
audio device and audio interface.
Notes
Quectel
Confidential
