A Research Of Microwave Self-oscillating Mixing Technology

With the research of the microwave technology,the demand for the microwave circuit miniaturization,low power consumption and low cost is increasing.Selfoscillating mixing technology provides the functions of a mixer and a local oscillator on a single active device.The application of the technology in the front-end of the receivers simplifys the structure of the circuits and lowers the cost.The technology shows great potential in many fields such as radar systems,radiometry,communication systems and so on.So it is necessary to make in-depth studies on self-oscillating mixing technology.The working principles and the dynamic of the development of the self-oscillating mixing technology were introduced in this paper.Based on the auxiliary source circuit,harmonic balance method which was analysed in detail was applied to simulation and optimization.An X-band self-oscillating mixer,a 2nd harmonic self-oscillating mixer and a 3rd harmonic self-oscillating mixer were developed to increase the conversion gain and the signal receiving sensitivity.Firstly,an oscillator was developed.After the analysis of the working principle of the oscillator,each part was designed in this paper,followed by an analysis of small signals and large signals.The oscillator,which lays the foundation of the self-oscillating mixer oscillates at the frequency of 12 GHz and the output power of 9.83 d Bm.Secondly,an X-band self-oscillating mixer with excellent performance was developed with the signal receiving sensitivity of-90 dBm and the maximum conversion gain is 5.5d B at-42 dBm.Harmonic self-oscillating mixing technology is a research in depth based on fundamental self-oscillating mixing technology.After analyzing the principles and characteristics of harmonic self-oscillating mixing technology,harmonic self-oscillating mixers were developed by balanced structure.A 2nd harmonic self-oscillating mixer with the output in phase realizes the signal receiving sensitivity of-90 dBm and the maximum conversion gain of 2.7dB.A 3rd harmonic self-oscillating mixer with the balun realizes the signal receiving sensitivity of-80 dBm and the maximum conversion gain of 3.5dB.Finally,Self-oscillating mixing technology was combined with PLL to increse the working stability and the conversion gain in this paper.After analyzing the working principles of PLL,based on the curcuit topology of the self-oscillating mixer,the implementation scheme of the PLL ciucuit was proposed.The PLL circuit with active loop filter was realized by single loop integer frequency division method and the X-band self-oscillating mixer was locked at 12 GHz.The final maximum conversion gain is 8.8d B.An intensive analysis and study of self-oscillating mixing technology conducted in this paper,is instrumental in miniaturizing circuit and has positive reference value.