Radio Part - Siemens S55 Repair Documentation

4 Radio Part

The radio part of the S55/S57, is using a Hitachi and an Infineon RF chip-set. This
manual covers the Hitachi chip-set.
The radio part is designed for Tripple Band operation, covering EGSM900, GSM1800
as well as GSM 1900 frequencies, and can be divided into 4 Blocks.
-Power supply for RF-Part
-Transmitter
-Receiver
-Synthesizer,
The RF-Part has it´s own power supply realised by a voltage regulator which is
located
inside the ASIC. The voltages for the logic part are generated by the Power-Supply
ASIC too.
The transmitter part converts the I/Q base band signals supplied by the
(EGOLD+) into RF-signals
recommendation (www.etsi.org) After amplification by a power Amplifier the signal is
radiated via the internal or external antenna.
The receiver part converts the received GMSK signal supplied by the antenna into IQ
base band signals which are further processed by the logic (EGOLD+).
The synthesizer generates the required frequencies for the transmitter and receiver. A
26MHz oscillator is acting as a reference frequency.
Restrictions:
The mobile phone can never transmit and receive in both bands simultaneously. Only
the monitor time slot can be selected independently of the frequency band.
Transmitter and receiver can of course never operated simultaneously.
V1.00
S55/S57
with characteristics
Page 6 of 49
Company Confidential © Copyright Siemens AG
as defined in the
ICM MP CCQ GRM
logic
GSM
12/02