SimCom SIM900 Hardware Design

SIM900 Hardware Design
It is suggested that you adopt one of the following two matching circuits in order to improve audio performance.
The difference audio signals have to be layout according to difference signal layout rules. As show in following
figures (Note: all components package are 0603.) If you want to adopt an amplifier circuit for audio, we
recommend National Company’s LM4890. Of course you can select it according to your requirement.
3.9.1 Speaker Interface Configuration
SPK_P
SPK_N
10pF
10pF
10pF
33pF
33pF
Close to speaker
GND
GND
Differential layout
33pF
ESD
ANTI
ESD
ANTI
MODULE
Figure 23: Speaker interface configuration
SPK_P
SPK_N
Differential layout
Amplifier
Circuit
10pF
10pF
33p
F
33pF
33pF
Close to speaker
GND
GND
10pF
ESD
ANTI
ESD
ANTI
MODULE
Figure 24: Speaker interface with amplifier configuration
SIM900_HD_V1.05 06.23.2010
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SimCom SIM900 Specifications

General

Brand	SimCom
Model	SIM900
Category	Modem
Language	English