WM_PRJ_Q2501_PTS_002
- 001
March
2004
confidential ©
Page:
17 / 79
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3 Functional Design
Some of the WISMO interface signals are multiplexed in order to limit the
number of pins but this architecture implies some restrictions.
All external signals must be inactive when the WISMO module is OFF to avoid
any damage when starting the module.
3.1 Power supply part
3.1.1 Main power supply and ground plane
3.1.1.1 Electrical
constraints
The main power supply (VBATT) is the only external power supply source used
to supply both the GSM/GPRS and GPS RF parts and Base Band parts.
The power supply is one of the key issues in the design of a GSM terminal.
Due to the bursted emission in GSM / GPRS, the power supply must be able to
deliver high current peaks in a short time (rising time is around 10 µs).
In communication mode, the GSM RF Power Amplifier current flows with a
ratio of (Figure 2):
•
Max current 1/8 of the time (around 577
µs every 4.615
ms for
GSM/GPRS class 2 – 2RX / 1TX),
•
Max current 2/8 of the time (around 1154 µs every 4.615 ms for
GSM/GPRS class 10 – 3RX / 2TX).
Summary of Contents for WISMO Quik Q2501
Page 69: ......
