Smart Machine Smart Decision
SIM800H _Hardware Design_V2.03
49
2016-10-10
R201, C201, C202 are the matching circuit, the value should be defined by the antenna design. Normally R201 is
1.2nH, C202 is 1.5pF and C201 are not mounted.
There are some suggestions for placing components and RF trace lying for GSM and Bluetooth RF traces:
The RF connector is used for conducted test, so keep it as close to pin GSM_ANT as possible;
Antenna matching circuit should be closed to the antenna;
Keep the RF traces as 50Ω;
The RF traces should be kept far away from the high frequency signals and strong disturbing source.
4.19.3.
FM Antenna Interface
The module provides 2 FM antenna pad named FM_ANTP and FM_ANTN, these are difference signal. The FM
antenna interface circuit is recommended as following:
Moudle
FM_ANTP
R303
C303
C304
R304
R301
C301
C302
R302
FM
Antenna
FM_ANTN
Figure 49: FM antenna matching circuit
Normally, R301\R302\R303\R304 are 0Ω, C301\C302\C303\C304 are not mounted.
The earphone is often used for FM antenna, as an example, the pin GND of the 3.5mm earphone is connected to
the FM interface. The circuit is recommended as following:
Moudle
GND
L301
R301
R303
C303
C304
C301
C302
FM_ANTP
FM_ANTN
Figure 50: GND pin of the earphone use to be the FM antenna interface
Normally, R301\R303 are 0Ω, C301\C302\C303\C304\L301 are not mounted.
SIMCOM
CONFIDENTIAL
FILE
