A frequency synthesizer includes a direct digital synthesizer (DDS), a digital-to-analog converter for converting the output of the DDS to a DDS output signal, a first bandpass filter for filtering the DDS output signal, a single side band mixer for mixing the filtered DDS output signal with a mixing...http://www.google.com.tw/patents/US6493410?utm_source=gb-gplus-share專利 US6493410 - Wide band high resolution synthesizer
