Maxon Electronics Australia Pty. Ltd. MM-5500U 用户手册
FCC Documentation- MM-5500U CDMA 1x/EVDO Modem
17/22
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5.4.1.1
Frequency synthesizing part
Frequency synthesizing part called PLL Synthesizer consists of three synthesizer circuit which is first
local synthesizer, Tx IF synthesizer and Rx IF synthesizer. The first local synthesizer generates the
primary local system oscillation frequency, operating over 1372.08 ~ 1419.54 MHz frequency range.
Tx IF and Rx IF synthesizer generate the second local oscillation frequency, 267.2 MHz and 367.2
MHz respectively.
5.4.1.2 Receiving
part
- Duplexer. The duplexer filters the RF signal transmitted through Antenna and sends the
signals to LNA.
-
LNA. This part in front-end is used to amplify the received signal with low noise figure
-
Down converter. It acts as a mixer using first local frequency to produce the desired signal
in the mid-range frequency of 183.6 MHz.
-
Rx AGC. This part is designed to control the gain of the dynamic range of midrange
frequency produced in down converter according 80 dB dynamic range.
Currently, previous BBA is divided into IFR3300(Rx IF-baseband converter) and RFT3100(Tx
baseband-IF converter). IFR3300 acts as the baseband analog processor which processing the
signals between the IFR3300 and digital processing circuit.
In the while, RFT3100 consists of Tx AGC and Tx part analog processor of previous BBA.
5.4.1.3 Transmission
part
- Tx AGC. It is designed to be gain-controlled from 84 dB dynamic range. The gain of this part
is controlled by MSM using digital control signal.
- Up converter. This part mixes the IF transmission frequency 138.6 MHz and the first local
1372.08 ~ 1419.54 MHz to generate transmission frequency of 824.64 ~ 848.37 MHz.
-
Power AMP module. This part is designed to work in 824 MHz ~ 849 MHz frequency range
in the CDMA mode and can generate the proper output power. The DC voltage into the power
amp module is typical 3.8V.