3. TECHNICAL BRIEF
- 63 -
3.21. RF synthesizer
The transceiver contains a fractional-N sigma-delta synthesizer for the frequency synthesis in the RX
operation mode. For TX operation mode the fractional-N sigma-delta synthesizer is used as Sigma-
Delta modulation loop to process the phase/frequency signal. The 26MHz reference signal is provided
by the internal crystal oscillator. This frequency serves as comparison frequency of the phase detector
and as clock frequency for all digital circuitry.The divider in the feedback path of the synthesizer is
carried out as a multi-modulus divider (MMD). The loop filter is fully integrated and the loop bandwidth
is about 100 kHz to allow the transfer of the phase modulation. The loop bandwidth is automatically
adjusted prior to each slot (OLGA
2
). To overcome the statistical spread of the loop filter element values
an automatic loop filter adjustment (ALFA) is performed before each synthesizer startup. The fully
integrated quad-band VCO is designed for the four GSM bands (850, 900, 1800, 1900 MHz) and
operates at double or four times transmit or receive frequency. To cover the wide frequency range the
VCO is automatically aligned by a binary automatic band selection (BABS) before each synthesizer
startup.
3.22. VCTCXO
The VCTCXO (X401) supply 26MHz reference clock and controlled by AFC input to generate a strict
system clock. The 26MHz clock is used to Transceiver(U402), Bluetooth chip(U102) and S-Gold2
(U102).
Figure32 VCTCXO Schematic
C431
22p
2V7_VCXO
X401
26MHz
2
GND
OUT
3
4
VCC
1
VCONT
0
R413
C430
1u
AFC
Содержание KE 770
Страница 1: ...Service Manual Model KE770 Service Manual KE770 Date April 2007 Issue 1 0 ...
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Страница 49: ...3 TECHNICAL BRIEF 50 3 15 BLUETOOTH Figure 22 BLUETOOTH Functional block diagram ...
Страница 57: ...3 TECHNICAL BRIEF 58 RF Block Diagram III 2 RF circuit ...
Страница 76: ...Check Points 5 Trouble shooting 77 ...
Страница 78: ...5 Trouble shooting 79 ...
Страница 82: ...5 Trouble shooting 83 ...
Страница 87: ...5 Trouble shooting 88 ...
Страница 100: ... 101 6 Download S W upgrade Click on the blue text to select the COM port ...
Страница 101: ...6 Download S W upgrade 102 Will change the window as below ...
Страница 103: ...6 Download S W upgrade 104 During download the screen will look something like this ...
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Страница 111: ... 112 8 PCB LAYOUT ...
Страница 112: ... 113 8 PCB LAYOUT ...
Страница 113: ... 114 8 PCB LAYOUT ...
Страница 114: ... 115 8 PCB LAYOUT ...
Страница 115: ... 116 8 PCB LAYOUT ...
Страница 117: ...9 RF Calibration 118 9 2 3 Click SETTING Menu 9 2 4 Setup Ezlooks menu such as the following figure ...
Страница 119: ...9 RF Calibration 120 9 2 7 Select MODEL 9 2 8 Click START for RF calibration 9 2 9 RF Calibration finishes ...
Страница 121: ...10 Stand alone Test 122 4 Click Update Info for communicating Phone and Test Program ...
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Страница 143: ...Note ...
Страница 144: ...Note ...