Development Of X-band Low Phase Noise Sapphire Dielectric Oscillator

With the rapid development of wireless communications and modern radar,the application of microwave frequency sources has become more and more widespread.As a core component of various microwave systems,the frequency stability and phase noise of oscillators add great significant to the overall performance of microwave systems.To develop a small,low phase noise,frequency stability of high-performance media oscillator is an urgent work.This article will develop a low-phase-noise,frequency-stable,small-sized dielectric oscillator that operates in the X-band.The author of this paper has read a large number of domestic and foreign literatures of the production of high-performance microwave frequency sources,and understood the research status at home and abroad,then summed up the experience and methods accumulated by the predecessors when developing dielectric oscillators,and then determined the design program of this design.In this paper,the dielectric oscillator has used a negative feedback oscillator model.The negative feedback oscillator model is consisted of a negative feedback network and a buffer amplifier.The negative feedback network consists of a dielectric resonator,a loop band-pass filter,a loop drive amplifier,phaser and coupler.When the gain and phase in the negative feedback network has satisfied certain conditions,the oscillator would start to vibrate.After determining the oscillator start-up conditions,the article used the ADS electromagnetic simulation software to simulate the phase noise and frequency stability of the oscillator circuit based on the LESSON phase noise equation and to analyze the effect of resonator Q and loop gain on system phase noise.Relying on the oscillator start-up conditions and LESSON phase noise formula,the article has assigned the index parameters of the system components.The working mode of this design sapphire dielectric resonator uses the whispering gallery mode,and the dielectric resonator operates with very high Q value at normal temperature.The article uses HFSS electromagnetic simulation software to weighed the effects of resonant frequency,Q value and differential loss on the phase noise of the system,then determined the size of the resonator,and determined the main mode of the resonator and the frequency of the heterojunction by analyzing the s parameters of the resonator.Then designed the loop-pass filter.Then,the phase shifter is designed so that the phase shifter can be continuously adjusted within the range of0-180~oin use frequency,and the phase shifter is adjusted so that the loop phase can satisfy the oscillator starting condition.Then the coupler is designed.After the design of the above components is completed,the difference loss has been weighted,and the loop drive amplifier is designed so that the loop gain satisfied the start-up condition of the oscillator.The loop amplifier is then designed based on the required output power,and simulation of the various components of the oscillator is completed.Completion of the work on the X-band,the phase noise of-110dBc/Hz@10kHz,-120dBc/Hz@10kHz,-130dBc/Hz@100kHz low phase noise dielectric oscillator development.