Fig.5: The IF Synthesiser (TX)
DIV
13
LOOP
FILTER
DIV 180
or 270
IC201 LMX2331L IF-PLL
PHASE
COMPARATOR
23-24
PHASE
DIFFERENCE
(CURRENT)
PHASE
DIFFERENCE
(VOLTAGE)
13MHz
CLK
8
1Mhz
1Mhz
GND
IC300
32
33
34
35
DIV2/3
18
16
180 or 270Mhz
180 or 270Mhz
D303B
D303A
540Mhz
31
PUPLO2
To W2013
GSM_TX
The TX IF Synthesiser
TX IF Synthesiser(IF-PLL) is the same PLL as used in the RX process and is
located within the LMX2331L (IC201). In this case the synthesiser is used to tune
the 540Mhz TX IF oscillator inside IC300.
The 540Mhz signal from IC300 is divided by a factor of 2 (for GSM) to produce a
270Mhz signal or divided by 3 (for PCN) to produce a 180Mhz signal.
This signal is then fed to #16 (IC201) and #9 (IC100) the TX modulator.
At IC201, it is divided down further by a factor of 180 or 270, dependant on which
tx band the mobile is set to. This produces a 1Mhz signal which is then input to a
phase comparator where it is compared with a 1Mhz signal derived from the
13Mhz clock to produce a current phase difference signal. This signal is output
from IC201 on #18 to the loop filter (C218, C219, R202, C228, R283, R204 &
L205), which aswell as filtering the signal also converts it to a phase difference
voltage. The phase difference voltage is then applied to the varactor network
(D303 A/B).
The varactor network forms part of the 540Mhz oscillator circuit inside IC300 and
is tuned by the applied voltage.
Содержание DB2000
Страница 1: ...DB2000 Service Manual Help ...
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Страница 4: ...Important One incorrect adjustment may result in the need for many more and result in extra 0 1 2 2 ...
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Страница 83: ...Fit Antenna INSERT AND SCREW THE ANTENNA INTO THE ASSEMBLY ...
Страница 106: ...Part 5 Test Signals Fig 3 4 V_G_LNA Pg 3 5I TP300 Fig 3 5 V_P_LNA Pg 3 5J TP301 Fig 3 6 RX_ON2 Pg 3 16G TP405 ...
Страница 107: ...Fig 3 7 GSM_LNA Pg 3 3I TP419 Fig 3 8 PCN_LNA Pg 3 3J TP420 Fig 4 9 TCXO Pg 2 H11 TP413 ...
Страница 108: ...Fig 4 0 GSM Rx I Q s Pg 3 E F15TP406 7 Fig 4 1 PCN Rx I Q Pg 3 E F15 TP406 7 Fig 4 2 GSM_TX Pg 1 1I TP403 ...
Страница 109: ...Fig 4 3 PCN_TX Pg 1 1J TP417 Fig 4 4 3V_G_TX Pg 1 4I TP100 Fig 4 5 3V_P_TX Pg 1 4J TP101 ...
Страница 110: ...Fig 4 6 GSM_ON Pg 1 2K TP402 Fig 4 7 PCN_ON Pg 1 1K TP415 Fig 4 8 PRE_ON Pg 1 4J TP416 ...
Страница 112: ... I Q ...
Страница 113: ...Fig 4 14 V_ERROR PCN Pwr Lvl 7Pg 1 16I Fig 4 15 300khz Charge Pump Pg 1 Log 9G ...
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