User Guide

GM47/48 Design Guidelines
BA/SEM/MSC 02:0006 Rev PA1 16
AFMS is the analogue audio output from the module. When it is active,
the output is derived from the PCM digital audio by the decoder part of
the CODEC. The PCM data comes from PCMI on the system
connector.
It is also used as an ear-piece driver for the Portable Hands Free
accessory.
Zout
4
(0.3 – 3.5 kHz)
≅ 120 Ω
Output capacitance
2.2 µF
Drive capability into 5 kΩ (0.3 – 3.5 kHz)
> 2.4 Vpp [TBC]
Drive capability into1.5 kΩ (0.3 – 3.5 kHz)
> 2.2 Vpp [TBC]
Levels
5
(THD<5%)
Drive capability into 150 Ω (at 1 kHz) > 1.3 Vpp [TBC]
Table 2. AFMS Levels. Audio Levels
3.6 RF and antenna Integration
The rules for RF and antenna integration are general good practice
guidelines i.e.
• Ensure the antenna is a good 50Ω match across the GSM 900/1800
bands for GM47 and GSM 850/1900 bands for GM48.
• Antenna installation should be, where possible, not close to large
metal objects as this will affect the matching mentioned above.
• A specifically designed antenna for the GSM signals being
operated at will ensure the best reception.
If these are followed there should be no issues in terms of RF.
Please also see section 6.6 regarding SAR.
4
Output impedance includes impedance of EMC filter which is 100 Ω.
5
Need to check output drive levels with 100R EMI filter.