- 76 -
C. Synthesizer
The RX and TX RF VCOs are fully integrated and self-calibrated on manufacturing tolerances.
They have 16 different frequency ranges that are selected internally depending on the frequency
programming. The calibration is done on each low to high logical transition of the SYNON bit in the
control register or on each change of the integer divider ratio of the RF fractional N synthesizer.
A high-performance RF fractional-N synthesizer PLL is included on-chip which enables the frequency
of the RF VCO to be synthesized. The frequency is set through the 3-wire serial programming bus.
The PLL is based on Sigma-Delta (∑) fractional-N synthesis that enables the required channel
frequency, including Automatic Frequency Control (AFC) from a free running external 26 MHz
reference frequency. Very low close-in-phase noise is achieved. This allows widening of the PLL loop
bandwidth and shorter settling time. The programmable main dividers are controlled by a second order
∑ -modulus controller. They divide the RF VCO signals down to frequencies of 26 MHz (12 Hz step
programmability). Their phase is then compared in a digital Phase/Frequency Detector (PFD) to the 26
MHz reference clock signal.
The phase error information is fed back to the RF VCO through the charge pump circuit that .sources.
into or .sinks. current from the loop filter capacitor, thus changing the VCO frequency such that the
loop finally gets phase-locked.
LGE Internal Use Only
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
VRADA_2V8
C217
56p
200
R206
C219
56p
C230
5.6p
5.6p
C225
VRADA_2V8
200
R208
5.6nH
L204
DNI
C218
VRADA_2V8
VRADA_2V8
SAFEB1G95KA0F00
FL202
2
G1
5
G2
3
G3
IN
1
OUT
4
9
10
TXQB
4
TX_1
VCCLORX
24
6
VCCLOTX
31
VCCRX
40
VCCTX
22
VDD
VGACTL
11
VDIGRAD_1V8
23
25
NC6
NC7
26
NC8
28
NC9
30
PGND
41
REFIN
15
38
RF_DAC1
RF_DAC2
39
17
RXIA
18
RXIB
19
RXQA
RXQB
20
21
TST
TXIA
7
8
TXIB
TXQA
CLK
DATA
12
EN
14
1
GNDTX
27
LNA1_IN
29
LNA1_OUT
35
MIX1_A
MIX1_B
36
2
NC1
32
NC10
NC11
33
34
NC12
37
NC13
NC2
3
NC3
5
16
NC4
NC5
SAFEB2G14FA0F00
2
G1
5
G2
1
IN
3
O1
4
O2
RF3100_OM6195HN
U204
13
FL201
200
R209
200
R207
4.7nH
L205
WRX_Q_P
WRX_I_N
WRX_I_P
WRX_BAND_1
WCLK
WPA_BIAS
WPA_VCC
WTX_I_P
WTX_I_N
WTX_Q_P
WTX_Q_N
WTXMOD_BAND_I
WRX_Q_N
RF_CTRL_CLK
RF_CTRL_DATA
RF_CTRL_STRB
Figure 3-7-4. WCDMA Transceiver schematic
Z3X-BOX.COM
Содержание KT520
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