Fig.2:The UHF Synthesiser (RX)
DIV
65
LOOP
FILTER
PRE-
SCALER
IC201 LMX2331L RF-PLL
(IC202/3)
PHASE
COMPARATOR
IN
OUT
3
2
4
3
5
PHASE
DIFFERENCE
(CURRENT)
PHASE
DIFFERENCE
(VOLTAGE)
13MHz
CLK
8
VCC
GND
1
NC
V_VC01/2
5
11,12,13
SERLT
SERCK
SERDA
EG :1205Mhz (GSM)
200Khz
200Khz
GND
GND
UHF VCO
UHF Synthesiser (Rx)
The RX & TX UHF Synthesisers are implemented within IC201- LMX2331L. The RX
UHF VCO output is fed to IC201 #5, where it is divided down (via a Prescalar) to a
200khz signal and input to a phase comparator. The phase comparator compares
this signal with a 200khz reference signal (which is derived down from the 13Mhz
clock). A current phase difference signal is produced, which is in turn converted to
a voltage phase difference and filtered at the output on #3, using the loop filter:-
(R205,R206,R207,C215,C216 & C217). This voltage is then applied to the
control input #3 of the UHF VCO (IC202/3). This voltage determines the RX UHF
VCO oscillator frequency, i.e.: RX GSM :1205 -1230Mhz / RX PCN:1535 -
1610Mhz. There are three control inputs for the UHF synthesiser:-
SERDA:
Synthesiser Programming Data (#12)
SERCK:
Synthesiser Programming Clock (#11)
SERLT:
:
Synthesiser Programming Enable (#13)
The SERDA input sets and controls the Pre-scalar inside IC201, this is totally
dependant on the chosen traffic channel that is active at the time.
Summary of Contents for DB2000
Page 1: ...DB2000 Service Manual Help ...
Page 3: ... ...
Page 5: ... 2 3 4 2 2 2 2 2 0 0 0 5 3 4 2 6 2 7 2 2 2 2 0 8 9 2 2 2 2 2 2 2 2 ...
Page 7: ... 2 6 2 2 2 2 2 3 4 2 2 0 2 ...
Page 8: ... 2 ...
Page 9: ... Previous Section Next Section Main Menu Section 2 Unit Specifications ...
Page 77: ... 1 2 ...
Page 83: ...Fit Antenna INSERT AND SCREW THE ANTENNA INTO THE ASSEMBLY ...
Page 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 ...
Page 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 ...
Page 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 ...
Page 112: ... I Q ...
Page 113: ...Fig 4 14 V_ERROR PCN Pwr Lvl 7Pg 1 16I Fig 4 15 300khz Charge Pump Pg 1 Log 9G ...
Page 115: ... Previous Section Next Section Main Menu Section 6 Device Device Information Information ...
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