Transmitter Part - LG CG225 Service Manual

3.3 Transmitter Part

The Transmitter part contains the transmitter parts of Si4210-GM[U502], Power Amp Module[U501]
and Front End Module[FL501]. The transmit section of Si4210-GM[U502] 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.
FL501
Front End Module
DCS
PCS
GSM 850/
EGSM
D
D
I
I
P
P
GSM 850/
EGSM
PA PA
RFOG RFOD
1
1
2
2
ANT_SW1,ANT_SW2
Figure 3. RF Transmit Block
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3. H/W Circuit Description
PAM RF3166 (U501)
DCS/ PCS
PA_BAND
IF PLL
IF PLL
RF PLL
RF PLL
2
2
DET
DET
Si4210 (U502)
Baseband
Baseband
(TI)
(TI)
U101
U101
IOTA
IOTA
Q
+
+
U102
U102
Calypso-
Calypso-
I