Design Of GaN Power Amplifier Based On Load-pull System

As the core of microwave systems,power amplifier determines the system performance to a certain extent.In order to adapt to the application of modern systems,the bandwidth requirements have become increasingly demanding,so the research of broadband power amplifier is of great practical significance.In the design method of power amplifier,the model method is widely used because of its convenient use and low design cost.However,the accuracy of models is limited,since they can not completely equivalent to the actual devices,and there is no simulation model in the early study of device.Load pull test provides a quick and effective alternative.In this paper,a method of designing a broadband power amplifier using load pull test technology is explored and studied based on the complete load pull test system of our laboratory,and a GaN broadband power amplifier is successfully designed.In this paper,the basic principle of power amplifier and the basic knowledge of load pull test system are introduced.The load pull test system is built based on the impedance tuner of focus,and the test precision is verified.A S band microwave test fixture is designed and manufactured to realize the connection between the transistor and the test system,and the prematching technique is adopted to improve the test precision.The cal kits are fabricated using the TRL(through-reflect-delay)calibration principle to remove the fixture parameters,so the test reference surface could be moved to the transistor pin to obtain its true parameters.Import the measured data into ADS software to design the stabilization circuit,the bias circuit and the impedance matching circuit of the amplifier.Use SolidWorks software to design the shield box of the amplifier.The measured results show that the amplifier has a small signal gain of14.2±1 dB in the operating frequency range of 2-3 GHz,and the output power of more than 40 dBm and the power added efficiency of more than 50% is achieved.The measured results of the amplifier are in good agreement with the load pull test,which verifies the feasibility and accuracy of the load pull test method for the design of broadband power amplifier.