TCL T728 Service Manual
TCL Mobile Communication
CO., Ltd
第
24
页
共
32
页
4.2 TX Part
After the voice signal is weaved and coded in baseband circuit, it forms equilibrium IQ signal
before entering U602. In U602, the IQ signal is processed before amplification in U600.The
amplifier (U600) is under the control of MT6205. After coming out from U600, the signal enters
into duplexer (U601). There, the electronic switch in U601 select the right frequency path to send
out the signal under the control of CPU. At last, the signal passes the
π
type network and is sent
out from antenna.
The transmitting process
：
Input of voice
（
MIC
）——
amplification
——
ADC
——
filter
——
Code of voice
——
weave
——
code
——
channel equilibrium
——
GMSK modulate
——（
Entering the RF circuit
）
IQ modulate
（
IQ modulator
）——
filter
——
Phase and frequency Detect
（
Phase and frequency Detector
）
——
filter
——
TX_VCO frequency converse
（
Mixer
）——
Power amplify
（
PA
）——
duplexer
——
matching circuit of antenna
——
send-out from antenna.
4.3 Power Amplifier
The role of circuit of power amplification is to amplify the modulated high frequency signal,
so that the signal has enough power to be emitted out from antenna.
；
The main pins of Power
Amplifier are: GSM-IN
、
GSM-OUT
、
DCS-IN
、
DCS-OUT
、
POWER-SUPPLY
、
POWER-LEVEL
ETC
。
RF3146 Features:
◆
Complete Power Control Solution
◆
Working at 2.9V
－
5.5V
◆＋
35dBm GSM Output power at 3.5V;
◆
＋
33dBm DCS/PCS Output Power at 3.5V
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