Research And Implementation Of Vector Mixer Calibration Algorithm

Mixer is one of the key devices in microwave and millimeter wave communication,radar and other systems.The performance of the mixer directly affects the performance index of the system.With the development of technology,the characteristic parameters of mixer are also gradually improved.So,how to measure the mixer's performance characteristics in high precision simply and conveniently has been an urgent problem.The mixer is a nonlinear device with three ports.The traditional amplitude measurement method by spectrum analyzer and dynamometer can only determine its amplitude characteristic,and can do nothing in phase frequency characteristics and group delay measurement.With the development of communication and radar technology,the group delay has become a key parameter.In this paper,the method of mixer measurement by Vector Network Analyzer(VNA)based on frequency offset is introduced,which can not only measure the frequency conversion loss of mixer,but also can measure the phase frequency characteristics of mixer.Vector Mixer Calibration algorithm(VMC)is adopted in the calibration period using calibration standards and a calibration of mixer/filter combinations to measure reflectance parameters,mixer conversion amplitude characteristic,phase and group delay.The process can mainly divide into three parts: the first part is to obtain characteristic parameters of calibration mixer/filter combinations using reflection method,and by extracting the ADS simulation data,the calibration of mixer/filter combination characterization algorithm are verified by MATLAB programming;the second part is the theoretical derivation of VMC,then simulate the test mixer,which parameters are known,to verify the calibration algorithm by MATLAB program calculation;the last part is to measured and obtained the parameters of the mixer by a VNA,then calculate the true parameter through error correction algorithm,and analyzes the influence on the measurement accuracy of the mixer under the condition that the calibration mixer does not meet the requirement of reciprocity,based on ADS simulation.In this paper,we researched and verified the VMC,based on Two-port Calibration algorithm,realized accurate measurement for conversion loss,phase and group delay characteristics of mixer.This work has important significance for microwave circuit and aviation field.