A High Performance Frequency Synthesis Method Based on PLL and DDS

A high performance frequency synthesis method based on PLL and DDS is introduced. The synthesized signal has the characteristics of high frequency tuning resolution, ultra-low phase noise and low spurious. The frequency synthesis method takes the wideband VCO as the frequency source of the PLL and the direct digital frequency synthesizer as the reference signal of the PLL. It has the characteristics of high frequency resolution and low phase noise of the direct digital frequency synthesizer, and improves the spurious level of the direct digital frequency synthesizer through the loop filtering ability of the PLL.