Maxon Electronics Australia Pty. Ltd. MM-5500SU ユーザーズマニュアル
FCC Documentation
MM-5500SU CDMA 1X/EVDO Modem
MM-5500SU CDMA 1X/EVDO Modem
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Confidential and proprietary information.
This document is the sole and exclusive property of Maxon Australia.
Not to be distributed or divulged without prior written agreement.
This document is the sole and exclusive property of Maxon Australia.
Not to be distributed or divulged without prior written agreement.
8. Description of circuit employed for suppression of spurious
radiation
In the CDMA transmit signal path, the frequency spectrum at the output of the CDMA DACs contains
unwanted frequency components due to the DAC output transition edges and transients. The
transmit clock frequency and harmonics are found in the spectrum.
Each CDMA DAC is followed by an anti-aliasing low-pass filter with a bandwidth of 630 KHz that
reduces unwanted frequency components installed in MSM5500. And then Tx IF frequency from the
RFT3100 is filtered by bandpass filter. The nominal specification of the filter is as following.
-
Nominal center frequency : 138.6 MHz
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3 dB Bandwidth : ± 630 kHz
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Stop band attenuation : 40dB min.
The Tx RF output of the Tx Mixer and the AGC amp is filtered again by the SAW band pass filter.
The nominal specification of the filter is as follows.
-
Pass band : 824 MHz ~ 869 MHz
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Attenuation : DC ~ 800MHz : 22 dB min.
869 MHz ~ 1049 MHz : 25 dB min.
1049 MHz ~ 2000 MHz : 19 dB min.
Finally, the spurious generated from Power AMP is filtered by the duplexer. The nominal specification
of the duplexer is as follows
-
TX Pass band : 824 MHz ~ 869 MHz
-
Attenuation : 869 MHz ~ 894 MHz : 40 dB min.