GSM/GPRS Module Series
M85 Hardware Design
M85_Hardware_Design Confidential / Released 48 / 88
Module
SPK2P
AGND
Differential layout
Amplifier
circuit
10pF
0603
10pF
0603
33pF
0603
33pF
0603
Close to Speaker
GND
GND
ESD
ESD
C2
C1
Figure 29: Speaker Interface Design with an Amplifier for AOUT2
The suitable differential audio amplifier can be chosen from the
Texas Instrument’s website
(http://www.ti.com/). There are other excellent audio amplifier vendors in the market too.
4.
The value of C1 and C2 here depends on the input impedance of audio amplifier.
3.8.4. Earphone Interface Design
1
2
4
3
SPK2P
MIC2N
MIC2P
22uF
68R
AGND
Close to Socket
Differential
layout
AGND
AGND
Module
4.7uF
ESD
GND
33pF
0603
10pF
0603
33pF
0603
GND
10pF
0603
ESD
Figure 30: Earphone Interface Design
NOTE