LG GT500 - Page 62

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Only for training and service purposes
LGE Internal Use Only
3. TECHNICAL DESCRIPTION
Figure 3-7-2. WCDMA Transmitter Architecture
3.7.2.1. Transmitter Part
The W-CDMA transmitter architecture is an on frequency linear direct up-conversion IQ-modulator.
The TX IQ modulator has differential voltage I and Q inputs. It converts input signals to RF output
frequency and is designed to achieve LO and image suppression. The in-phase and quadrature-phase
reconstruction filters are fully integrated and a programmable gain amplifier implements the gain control.
The transmit output stage provides at least +5 dBm at maximum power control at the single-ended 50 
output. Gain is set through the 3-wire bus. An external SAW filter between the W-CDMA circuit and the
power amplifier is used to improve noise performance. Two 10-bit DACs are used to control the DC/DC
converter and the PA gain. After the power amplifier, the signal is sent through an isolator and through the
duplex filter, which directs the transmit signal to the antenna connector through the antenna switch. The
supply voltage and bias of the power amplifier are adapted depending on the output power to achieve
high efficiency at every transmitter power level. A high efficiency DC/DC converter regulates the supply
voltage and the bias operation point is controlled by a D/A-converter in the W-CDMA radio circuit.
These DACs are controlled through the 3-wire-bus
GSM/EDGE
PA + Ant Sw.
ANT
VAPC
RADCLK
RADDAT
RADSTR
VBAT
2.75 V
VRAD
1.8 V
VIO
PA
PA
GSM850/
900 Input
DCS/PCS
Input
ESD
2.75 V
VRAD
LNA
LNA
LNA
LNA
LNA
A
D
A
D
0
90
LPF
+
ChP PhD
÷
N.M
VCO
LPF ChP PhD
÷
N.M
+
0
90
+
DAC
DAC
XO
DAC
VCO
VCO
LNA
LNA
WCDMA LB
WCDMA HB
WCDMA HB
WCDMA HB
CLK
DATA
STROBE
Serial
Control
WTxQB
WTxQA
WTxIB
WTxIA
GSM/EDGE
AM
DAC
RFCtrl1
RFCtrl2
RFCtrl1
RFCtrl2
GSM/
EDGE HB
GSM/
EDGE LB
WCDMA LB
WCDMA HB
WCDMA HB
GSM/EDGE
LB
GSM/EDGE
LB
GSM/EDGE
HB
GSM/EDGE
HB
WRxIA
WRxIB
WRxQB
WRxQA
EDataA
EDataB
EDataC
EDataStr
WCDMA/GSM/GPRS/EDGE TRX
MCLK
CLKREQ
MCLKSec
XO
XOn
XOp
26MHz
X-tal
VBAT
VccWPA
VccWPA
Power
coupler
Power
coupler
VccWPA
VccWPA
Bias
DET
En
DET
Bias
DET
En
UL: 1920 – 1980 MHz
DL: 2110 – 2170 MHz
UL: 1749.9 – 1784.9 MHz
DL: 1844.9 – 1879.9 MHz
UL: 830 – 840 MHz
DL: 875 – 885 MHz
824 – 915 MHz
1710 – 1910 MHz
1930 – 1990 MHz
1805 – 1880 MHz
925 – 960 MHz
869 – 894 MHz
WDCDCREF
FB
Switch
PWM/PFM
En
Cont rol
Logic
RFCtrl1