Design And Implementation Of A New Type Digital And Programmable Frequency Synthesizer

Phase locked loop is based on frequency synthesize method of phase lock technology. It utilizes good narrowband track of the phase lock loop characteristic, which makes output frequency lock highly level off reference frequency or hypo-highly concordant wave, that makes locked frequency in accordant with frequency stabilization and spectrum purity of the reference frequency. The direct digital frequency synthesizer is a kind of fully digitized frequency synthesizer, which consists of the phase accumulator, the sine wave look-up table, the digital to analog converter. It is of high frequency resolution, fast frequency switching speed, low phase noise, the ability to switch frequencies while maintaining constant phase, and the ability to producing arbitrary waveforms. Because of above features, direct digital frequency synthesizer can be used in such fields as radar, communications, electronic warfare and electronic measurement instruments. After comparing both of technique of digital frequency, we choose the direct digital frequency synthesis hybrid phase locked loop solution to produce high-performance, and functionally-integrated 460MHz-480MHz signal with high frequency resolution, low phase noise and spurious.First, we introduce the basic structure, work principle and ideal frequency spectrum of the phase locked loop and the direct digital frequency synthesizer, especially summarize noise source of frequency synthesizer. In the light of their properties, we analyze the loop part factors in phase locked loop, also analyze the influences generated by the phase truncation and amplitude quantization of sinusoid and by the transform error of DAC in phase locked loop. Then we analyze performance from frequency synthesis technique of the direct digital frequency synthesizer inspire phase locked loop. Direct digital frequency synthesizer has merits with output step little and well-phase noise, but low spurious. However, phase locked loop can remedy these demerits of the direct digital frequency synthesizer, give the design methods of direct...