Study On GaN Power Amplifier Junction Temperature Prediction Model And Junction Temperature Optimization

GaN power amplifiers are widely used in the new generation of communication RF technology and are the core components in mobile communication RF technology.However,as the field of mobile communication technology develops towards high power,high capacity,high transmission efficiency and high integration,it will inevitably bring great heat dissipation challenges to the power amplifier chip,making the problem of high chip junction temperature increasingly prominent.The high junction temperature of the chip can cause a series of failures in the chip,which can seriously affect the performance of the power amplifier.To this end,this thesis addresses the problems of obvious self-heating effect,high power density and high integration of GaN power amplifier chips in the new generation of communication RF technology,researches and analyses the heat transfer performance of GaN power amplifier single chip and multi-chip,and establishes a GaN power amplifier junction temperature prediction model considering thermal diffusion and thermal coupling effects on the basis of the traditional thermal resistance network model.The accuracy of the multi-chip junction temperature prediction model is verified by comparison with experimental measurements,and has a higher chip junction temperature prediction accuracy than the traditional thermal resistance network model for different thermal conditions.In addition,on the basis of the thermal analysis of GaN power amplifiers,the package parameters are optimised for chip junction temperature,providing a reference for chip thermal design and package optimisation.The main research work and conclusions are as follows:(1)The research revolves around the junction temperature prediction model of GaN power amplifier single chip.By simplifying the structure of GaN power amplifier thermal test chip,a GaN power amplifier thermal simulation model is established;by studying the heat dissipation of the chip under natural working environment,the natural convection heat transfer coefficient of the chip is obtained and the main path of heat transfer of the chip is analyzed;by studying the variation of heat flow density in the vertical path of the GaN power amplifier thermal source chip,based on the traditional thermal resistance network model,a The junction temperature prediction model is compared with the experimental results to verify the accuracy of the model,which has higher junction temperature prediction accuracy compared with the traditional thermal resistance network model.(2)The GaN power amplifier multi-chip junction temperature prediction model is studied.On the basis of the single-chip junction temperature prediction model,the cross-coupling phenomenon of the heat flow path of two heat source chips is studied and analyzed,and based on the principle of linear superposition,a GaN power amplifier multi-chip junction temperature prediction model considering thermal diffusion and thermal coupling effects is established by sequentially superimposing other chips on their thermal coupling temperature rise.The accuracy of the multichip junction temperature prediction model is verified by comparing with the experimental measurement results,and the accuracy is higher compared with the traditional thermal resistance network topology model.(3)Optimization of chip packaging parameters around the junction temperature of GaN power amplifiers.Based on the thermal analysis of GaN power amplifier,the response surface regression equation of the relationship between the main structural parameters of the chip and the junction temperature of the chip was established through the study of the influence of the chip layout,material thermal conductivity,structure thickness,thermal vias and other factors on the junction temperature of the chip.The response surface regression equation was used to optimize the junction temperature of GaN power amplifier chips.