Research On Ultra-wideband Low Phase Noise Frequency Source Based On Frequency Shift Phase Lockin

As the core component of the electronic system,the frequency source directly affects the performance index of the system.Combining the advantages of each frequency synthesis technology,this paper proposes a dual phase-locked loop scheme based on the frequencyshifting and mixing structure by mixing a variety of techniques.The design of 0.1～22GHz ultrawideband small step low phase noise frequency source is realized.First,a frequency-shifting mixing loop is developed through a phase-locked loop interpolating multi-stage mixer scheme.The high-resolution narrow-band reference signal is used as the local oscillator signal of the mixer through the frequency multiplication/frequency division group,and the phase-locked loop can output 5650～11300MHz signal and the loop frequency division is realized by rationally planning the frequency multiplication/frequency division group and the output frequency band.The ratio is fixed at 1,and finally,the output frequency of the phase-locked loop is expanded by using the direct frequency synthesis technology to realize the full-band output of the system.Second,a single-stage mixer scheme is interpolated through a phase-locked loop to provide a narrow-band low-phase-noise reference signal for the frequency-shifted mixing loop.In order to solve the problem of output frequency resolution,the DDS excitation PLL scheme is adopted,and the DDS output resolution is high.Then,due to the introduction of multi-stage mixers and divide/multiplier groups in the system,many switches are also involved.In order to ensure the fast response of the system when switching frequency points,a configuration algorithm for system parameters is designed,which can accurately calculate the variable parameters in the scheme.Finally,based on this scheme,the chip selection,theoretical calculation and simulation research are completed,the feasibility of the scheme is verified,and the physical design is completed.After testing,the frequency source can realize the output frequency range of0.1～22GHz,and the frequency resolution is 1Hz.When outputting a 22 GHz signal,the phase noise can reach-109 d Bc/Hz@10k Hz.Spurious suppression is better than 60 dBc.