Customer Care
V 1.0 Page 15of 52 ICM MP CCQ GRM
SL55
Company Confidential © Copyright Siemens AG
06/03
4.5 Transmitter
4.5.1 Transmitter: Modulator and Limited Amplifier
The GMSK modulated signal is generated in the direct modulator. That means, that the
modulators are working directly on the final output frequency. The LO frequency is divided
by 2 or 4, depending on the GSM band. There are two modulators, one for the two higher
bands and the other for the two lower bands..
The required voltages VREGRF1 and VREGRF2 are provided by the ASIC D361
The actual signal is fed into a limiting amplifier with 3 dB amplification which also provides
a signal path for the high band and one for the low band.
Mode Selection Pin9 / EN (TXON1/D171_J14)) Pin10 / BS (OSW1/D720_25)
EGSM900 limiter enable HIGH LOW
GSM1800 limiter enable HIGH HIGH
Top View IC Overview
The next stage in the low band line-up is a TX saw filter.
to P
from EGOLD+
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