Research On Load-pull Measurement Technique For RF Power Amplifiers

The wireless communication technology is continuously developing,and the industry has increasingly higher performance requirements for RF power amplifiers.Load pull can provide a reliable reference for matching network design of RF power amplifier circuits,and became a research hotspot in wireless communication applications.In this paper,different types of load pull measurement systems were studied,and a complete set of load pull and load mismatch measurement scheme was built as well as practical experiments for verification were conducted.The main content of the paper can be divided into the following sections:1.The structure and operating principle of common RF power devices were introduced,and this leads to the principle and basic procedure of load pull measurement.The components of system corresponding to various load pull measurement technique solutions,as well as the strengths and weaknesses and the applicable scenes were discussed.2.The tuning mechanisms of passive,active and hybrid load pull measurement techniques were discussed,the calibration and application methods were also highlighted.In addition,the in-situ system calibration method for passive load pull systems and the power calibration method for active load pull systems were studied in detail,and the problem of parameter selection for assessing the accuracy of calibration results was also discussed.3.The multi-tier calibration methods in load pull measurement were introduced comprehensively,the phase shift of fixture de-embedding in the multi-tier TRL calibration method was discussed,and the optimized algorithm was proposed.The universality and effectiveness of the algorithm were verified through practical experiments of the HEMT devices eventually.4.The ruggedness test methods based on load pull measurement for conventional and improved VSWR circles were proposed.The advantages of the improved VSWR circle test method in the performance evaluation of the device were demonstrated through practical experiments,and the mismatch characteristics of the HBT devices were analyzed by the vector data obtained from fundamental and harmonic load mismatch measurement.