Baseband Design
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This document is the sole and exclusive property of WAVECOM. Not to be distributed or divulged
without prior written agreement.
WM_PRJ_Q24NG_PTS_002-001 June
2006
Figure 3: Burst simulation circuit
3.1.2.3 Battery integration
The Q24NG may be directly connected to a Li-Ion battery (3.7 V typical
voltage, with internal PCM – Protection Circuit Module). The internal
impedance of the battery must be lower than 150 m
Ω
to limit voltage drop-
out within emission burst (max. drop 0.3 V @ 2W).
Battery internal impedance must take into account:
•
the internal impedance of the battery cell,
•
the protection circuit impedance,
•
the “packaging” impedance (contacts),
•
the PCB track impedance up to the Wireless CPU pin.
3.1.2.4 External DC power supply
The Q24NG may be connected to DC power supply directly or via a DC/DC
converter on the mother board. The internal impedance of the power
supply must be lower than 150 m
Ω
to limit voltage drop-out within
emission burst (max. drop 0.3 V @ 2W).
This impedance must take into account:
•
the internal impedance of the power supply,
•
the protection circuit impedance,
•
the “packaging” impedance (contacts),
•
the PCB track impedance up to the Wireless CPU pin.
Linear regulation (recommended) or PWM (Pulse Width Modulation)
converter (usable) are preferred for low noise.
Warning:
PFM (Power Frequency Modulation) or PSM (Phase Shift Modulation)
systems must be avoided.
