LG MG220, Service Manual

Page: 18 / 130

3. H/W Circuit Description
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3.3 Transmitter Part
The Transmitter part contains the transmitter parts of Si4210-GM[U501], Power Amp Module[U501]
and Front End Module[FL500]. The transmit section of Si4210-GM[U501] consists of an I/Q base band
up_converter, an offset phase-locked loop(OPLL) and two output buffers that can drive external power
amplifiers(PA).
The RF GMSK outputs from the transmit VCO are fed directly to the RF power amplifiers. The peak
output power and the profile of the transmitted burst are controlled by means of incorporated pow er
control circuits inside of PA and DAC output from the Base band Controller. The PA outputs pass to
the antenna connector via Front End Module.
DET
DET
2
2
1
1
2
2
IF PLL
IF PLL
I
Q
Baseband
(TI)
U100
IOTA
+
U101
Calypso-
Baseband
(TI)
U100
IOTA
+
U101
Calypso-
PA_BAND
ANT_SW1,ANT_SW2
RFOG RFOD
GSM 850/
EGSM
DCS/ PCS
RF PLL
RF PLL
D
I
P
D
I
P
DCS
FL500
Front End Module
PCS
GSM 850/
EGSM
Si4210 (U501)
PAM RF3166 (U500)
PA PA
Figure 3. RF Transmit Block
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