| Gallium nitride(GaN),as the representative of the third generation wide band gap semiconductor,has large band gap width(3.4e V)and high critical field strength(3×10~6V/cm),high electron mobility(2×10~7cm/s)and other advantages have become the research hotspot of research institutions since its birth.Compared with gallium arsenide(Ga As)devices,GaN microwave power devices can achieve higher output power,better frequency bandwidth and higher power conversion efficiency,which is the focus of competitive research in the United States,Europe,Japan and other countries.After nearly two decades of development,Al GaN/GaN HEMT based on Si C substrate has gradually matured,but there are still many problems and challenges in the development,modeling and circuit application of high-power devices.The content of this paper is to study the layout design,device modeling and internal matching circuit design of GaN high-power microwave power HEMT.The main work and innovations of this paper are as follows:(1).A high reliability design method of GaN high power device layout and structure is proposed.According to the structure of the device with large gate width,the effects of the single finger gate width,the number of cells,the layout and thermal design of the device on the performance and reliability of the device are studied and clarified,and the high reliability design of the high-performance device is realized.The breakdown voltage of the designed microwave device with large gate width is greater than 300V,which meets the working conditions of the amplifier at 100V.(2).A high-precision model of GaN device is proposed.By studying the equivalent circuit model of GaN devices and the extraction method of various parameters in the model,the size signal model of GaN devices is extracted.In order to improve the accuracy of GaN device model,a new model topology is proposed.Using virtual resistance Ri,the fitting accuracy of device model and measured data is improved,and the accuracy of small signal model of large gate width devices at different frequencies is improved;Through the research of eehemt model and the extraction of parameters,the accuracy of large signal model of large gate width GaN devices is realized,which meets the needs of broadband circuit design of large gate width devices.The L-band and Ku-band high-power amplifiers designed with this model have excellent test performance,and the accuracy of this model is verified.(3).A heterogeneous integration method of microwave high power devices is proposed.This paper discusses the design process and steps of L-band and Ku-band internal matching power amplifiers in detail,and discusses and summarizes the factors that need to be considered in the amplifier design from the aspects of overall design,matching circuit design,bias circuit,stability and packaging design.The GaN HEMT is heterogeneously integrated with the Ga As passive circuit,and the input inductance,capacitance and RC stable network are integrated on the Ga As substrate to realize the design of quasi monolithic integrated circuit,which greatly improves the integration,consistency and economy of the whole amplifier.The designed L-band power amplifier has the advantages of miniaturization,high efficiency and good consistency,and meets the requirements of mass production in engineering.The above research work improves the design accuracy,microwave performance index,reliability and consistency of GaN high-power devices,and promotes the application of GaN microwave high-power devices. |
