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Power Supply
Power Supply Description
The power supply is one of the key elements in the design of a GSM terminal. Due to the burst
emission in GSM/GPRS, the power supply must be able to deliver high current peaks in a short time.
During these peaks, the ripple (U
Table 4 Input Power Supply Voltage for the input power supply voltage values.
Listed below are the corresponding radio burst rates for the different GPRS classes in
communication mode.
•
A GSM/GPRS class 2 terminal emits 577μs radio bursts every 4.615ms. (See Figure 5 Power
Supply During Burst Emission.)
•
A GPRS class 10 terminal emits 1154μs radio bursts every 4.615ms.
VBATT provides for the following functions:
•
Directly supplies the RF components with 3.6V. It is essential to keep a minimum voltage
ripple at this connection in order to avoid any phase error.
•
The peak current (TBDA peak in GSM/GPRS mode) flows with a ratio of:
1/8 of the time (around 577μs every 4.615ms for GSM/GPRS class 2)
and
1/4 of the time (around 1154μs every 4.615ms for GSM/GPRS class 10)
with the rising time at around 10μs.
•
Internally used to provide, via several regulators, the supply required for the baseband
signals.
WA_DEV_W228_PTS_002
) on the supply voltage must not exceed a certain limit. Refer to
ripple
Figure 5. Power Supply During Burst Emission
Rev 001
Product Technical Specification &
Customer Design Guidelines
Page 27 of 108
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