The Design Of X-band Receiver Based On Self-Oscillating Mixer

In recent years,with the continuous research and development of microwave wireless communication technology,the design requirements for microwave wireless communication systems are constantly developing in the direction of high performance,miniaturization,integration,low power consumption and low cost.As the main part of microwave wireless communication system,the design of miniaturization and integration of receiver link is also concerned.Oscillator and mixer,as the key circuit units to realize frequency conversion in the traditional wireless receiver link,usually have complex circuit structure and large area,which is not conducive to miniaturization design.Selfoscillating Mixer(SOM)can use a single active device to generate an oscillating signal and use it as a reference frequency to achieve the function of frequency conversion.It provides new ideas and methods for miniaturization and low-power design of receiver links.In this thesis,based on the traditional superheterodyne receiver structure,an Xband receiver RF front-end circuit structure based on the self oscillating mixer is proposed,which has smaller circuit area and lower power consumption compared with the superheterodyne receiver structure.In this thesis,the main receiver system structure is introduced and the main technical parameters to measure the performance of the receiver is analyzed.On this basis,the design scheme of the X-band receiver RF front-end circuit system based on SOM and the key design parameters of all levels of circuit units are determined.In this thesis,the key technical specifications of the design of LNA are analyzed,determines the design scheme and parameters of the LNA in X-band are determined,the design methods of each part of the LNA circuit are analyzed in detail,and the simulation design and PCB test of the X-band LNA are completed.The test results show that: in the working frequency range of 10.0~10.5GHz,the noise figure of the designed LNA is less than 1.6dB,the gain is greater than 18.2dB,and the VSWR of input and output ports is less than 1.5.Then the related design theory of negative resistance oscillator is analyzed,each part of the circuit of X-band negative resistance FET oscillator is analyzed and designed,and the design and PCB of the oscillator circuit are completed.The test results show that: the measured frequency of the oscillator is about 12.01 GHz,the output power is about 10 dBm,the second harmonic suppression is greater than 20 dBc,and the phase noise at a frequency offset of 100 KHz is better than-94dBc/Hz.In this thesis,the basic theory of the negative resistance oscillator is analyzed.The simulation design and PCB test of the X-band negative resistance oscillator are completed.The test results show that: the oscillation frequency is about 12.01 GHz,the output power is about 10 dBm,and the phase noise at the frequency offset of 100 KHz is better than-94dBc/Hz.On this basis,the design scheme and index of the X-band self oscillation mixer are determined.At the same time,the image suppression filter and the intermediatefrequency filter are designed.The simulation design and PCB test of the X-band self oscillation mixer are completed.The test results show that: within the RF input signal range of 10.0~10.5GHz,the intermediate frequency signal output range of the designed self-oscillation mixer is about 1.5~2.0GHz,the conversion gain is greater than 3dB.In this thesis,the overall design and PCB test of the RF front-end circuit of X-band receiver are completed,and the test results meet the expected design targets.The feasibility of miniaturization and low-power design of receiver system using selfoscillating mixing technology is verified,which has a certain engineering application value.