TCL T728, Руководство по обслуживанию, Страница: 23 / 32

TCL T728 Service Manual TCL Mobile Communication CO., Ltd
第 23 页 共 32 页
Fast setting time suitable for multi-slot GPRS application
Supporting Multilane
：
GSM850 Class 4,small MS
E-GSM900 Class 4,small MS
PCS1800 Class 1
PCS1900 Class 1
GPRS
Class 12
3 bus-interfaces
General description
：
MT6129 is a highly integrated RF transceiver IC for multi-band Global Systems for Mobile
communication (GSM) and General Packet Radio Service (GPRS) cellular system applications.
The MT6129 includes four LNAs, Two RF quadrature mixers, an integrated channel filter,
programmable gain amplifiers (PGA), an IQ demodulator for the receiver, a precision IQ
modulator with offset PLL for the transmitter, two internal TX VCOs, a VCXO, on-chip regulators,
and a fully programmable sigma-delta fractional-N synthesizer with an on
– chip RF VCO.
4.1 RX Part
The receiving of signal includes the receiving and processing of the three band: GSM band 、 DCS
band and PCS band 。 Of course, the phone cannot receive this three band at the same time. They
will be coupled to duplexer U601 at the different time after passing through the antenna E600, π
type filtering network, antenna coupling testing-end J600, C620.As the frequency is certain while
receiving the signal at the moment, the CPU will control the U601 to select the relative path to
output a certain frequency(See the following diagram)
；
The frequency will be processed by
different SAW filter, then it will change into equilibrium wave from an un-equilibrium wave
before passing through frequency-select filter and entering MT6129 （ U602 ） . The IQ signal is
outputted from U602 after the signal passing through the LNA
、
MIXER
、
PGA
、
CHANNEL
FILTER 、 IF MIXER 、 AMPLIFIER 、 IQ DEMOD (all is inside of U602 ) 。 The gain of IQ signal
is effected by SEN 、 SDATA and SCLK ,and is under the control of AGC ,which can make the
LAN of RX to produce a steady output.
The receiving process ：
Receiving of antenna
——
matching circuit of antenna
——
duplexer
——
filter
（
SAW filter
）——
amplification （ LNA ）—— RX_VCO （ Mixer ）—— amplification （ PGA ）—— filter —— IQ
demodulation(IQ modulator)
——（
Base-band part
）
GMSK demodulation
——
signal equilibrium
—— decoding —— de-weaving —— audio decoding —— filter —— DAC —— amplification ——
output of voice
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