LGE Internal Use Only
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
3.4 LO generation and distribution circuits
The integrated LO generation and distribution circuits are driven by internal VCOs to support various
modes to yield highly flexible quadrature LO outputs that drive all GSM and UMTS band upconverters
and downconverters; with the help of these LO generation and distribution circuits, zero-IF architecture
is employed in all GSM and UMTS band receivers and transmitters to translate the signal directly from
RF to baseband and from baseband to RF.
Two fully functional fractional-N synthesizers, including VCOs and loop filters, are integrated within the
RTR6275 IC. The first synthesizer (PLL1) creates the transceiver LOs that support the UMTS
2100/1900/1800 transmitter, and all four GSM band receivers and transmitters including: GSM 850,
GSM 900, GSM 1800, and GSM 1900.
The second synthesizer (PLL2) provides the LO for the UMTS 2100/1900/1800 receiver. An external
TCXO input signal is required to provide the synthesizer frequency reference to which the PLL is
phase and frequency locked. The RTR6275 IC integrates most of PLL loop filter components on-chip
except two off-chip loop filter series capacitors, and significantly reduces off-chip component
requirement. With the integrated fractional-N PLL synthesizers, the RTR6275 has the advantages of
more flexible loop bandwidth control, fast lock time, and low-integrated phase error
3.5 Off-chip RF Components
3.5.1 WCDMA PAM (U104: WS2512 TR1G)
The UMTS PA output power is monitored by l power detector circuits(U101 : RTR6275) .
This detector voltage can be used for transmitter calibration and monitor to meet RF system
3. TECHNICAL BRIEF
- 25 -
[Figure 1.5] WCDMA PAM, Duplexer, Coupler
WCDMA
20dB
7dB
U103
CP0402A1950DNTR
50OHM
4
3
COUP
2
IN
1
OUT
2
45
31
KRX102U
TR100
2.7nH
L114
L115
5.6nH
130
R121
NA
L118
C164
3.3nH
FL102
ACMD-7602
ANT
3
PGND
4
1
RX
TX
2
NA
C160
2
G1
3
G2
5
G3
1
IN
4
O1
FL101
EFCH1950TDF1
100p
C167
3.3p
C162
R119
51
L122
1.8nH
0.01u
C158
L116
2.2p
1u
C435
33p
C155
47
R120
0.01u
C159
C156
4.7u
R122
130
C165
10nH
3
GND2
6
7
GND3
9
GND4
RFIN
2
RFOUT
8
1
VCC1
VCC2
10
4
VCONT
5
VREF
WS2512_TR1G
U104
11
BGND
GND1
+VPWR
+VPWR
PA_R0
PA_ON
VREG_TCXO_2.85V
PWR_DET
Содержание U370
Страница 1: ...Date January 2008 Issue 1 0 Service Manual Model U370 Service Manual U370 ...
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Страница 147: ... 148 LGE Internal Use Only Copyright 2007 LG Electronics Inc All right reserved Only for training and service purposes ...
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Страница 178: ...Note ...
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