Research On Very Low Phase Noise Frequency Stabilization Technique

Microwave oscillators are devices that generate signals in many microwave systems.Precise oscillators are needed in many fields such as radar,navigation,communications,and remote sensing.The frequency stability of the oscillator directly affects and determines the performance of these systems.Therefore,research on oscillator frequency stabilization technology has always been a topic of concern for scientists and technicians.In this paper,a high Q air resonator is used as a frequency discriminator,and a very low phase noise stabilization system is designed to improve the phase noise of the output point of a dielectric voltage controlled oscillator by using the carrier suppression technique.The specific research work includes the following aspects:1.First,a reference index for identifying the stability performance of a point frequency signal is introduced,including frequency accuracy and frequency stability.Then,starting from the concept of oscillator principle and frequency stability,the classical Leeson model for phase noise is introduced and described.A brief deduction process.2.Enumerate several commonly used frequency stabilization techniques such as crystal temperature compensation,frequency stabilization,loop injection and phase lock frequency stabilization,loop sampling and phase lock frequency stabilization,frequency locking loop frequency stabilization,and high Q transmission cavity frequency stabilization,and The respective characteristics of these several kinds of theories;then based on this,the extremely low phase noise frequency stabilization technology studied in this paper is introduced and analyzed theoretically.3.Based on the basic theory of cylindrical air resonant cavity,a high-Q cylindrical air resonant cavity is designed as a key component of the very low phase noise frequency stabilization system.The resonant cavity excitation port adopts a coaxial-waveguide conversion device.In order to achieve a good carrier suppression effect,in use,the input port of the resonant cavity is adjusted to be close to the critical coupling state,and the output port is adjusted to a weakly coupled state.4.Referring to the framework of the very low phase noise frequency stabilization system,we have simulated and fabricated active and passive devices for extremely low phase noise frequency stabilization systems,including: dielectric voltage controlled oscillators,power amplifiers,directional couplers,3 dB Bridges,phase shifters,mixers,loop filters,adders,etc.,and tested for various device performance parameters.5.The use of successively added devices was used to set up and debug the extremely low phase noise frequency stabilization system.After testing,a point frequency source composed of a frequency stabilization system outputs a point frequency signal having a frequency of 9.9071 GHz and a power of 7.17 dBm.The spurious of the point-frequency signal are within the noise power at the test frequency band of the instrument,and the phase noise is-72.2 dBc@1 KHz,-99.8 d Bc@10 KHz,-117.8 dBc@100 KHz,and-131.8 dBc@1 MHz,respectively.