Research On Wideband Low Phase Noise Agile Frequency Synthesizer

In the coherent radar system,the phase relationship between the signals is required to be determined in order to extract the Doppler information.As a feedback control circuit,the PLL technology can be used to control the frequency and phase of the external signal,so it can be applied to the coherent radar.In order to realize the detection and tracking of radar target,it is required to have broadband,low phase noise,rapid frequency conversion and miniaturization.Coherent radar system,this paper to the requirement of PLL,combined with domestic and foreign development present situation,design and implements a miniaturization of 1?13 GHz broadband output phase-locked loop,and realize the low phase noise and fast hop,and the miniaturization is realized.According to the requirement of low phase noise and broadband output,a dual-chip scheme is proposed.The wideband output phase-locked loop chip with integrated voltage-controlled oscillator is used as a phase detector for VCO.Using HMC704 and ADF4355,the broadband output and the measured phase noise are better than the ADF4355 single chip,and the phase noise of 1 kHz is optimized 6dB at 3GHz and 6GHz outputs.According to the requirement of fast hop and miniaturization,the switching loop filter scheme is proposed.When the PLL is unlocked,the broadband loop filter access circuit realizes fast locking,and then switches to a narrow band loop filter to achieve better phase noise and stray indicators.Because of the single ring structure,the miniaturization is realized.Finally based on the two scheme,design has realized the two paragraphsl?13GHz output source with low phase noise and fast hop,HMC698 chosen as the phase detector,ADF5355 and LMX2594 respectively as the VCO,all meet the requirements.The measured phase noise of the 13GHz output is superior to-95dbc/Hz.The lock time is less than 20?s.The frequency synthesizer developed in this project has the characteristics of low cost,miniaturization and high performance,and has a broad prospect of engineering application.