Electro-Thermal Coupling Simulation Of GaAs HBT RF Power Amplifier

The rapid development of modern wireless communication technology has led to the important position of RF PA.Gallium arsenide(GaAs)heterostructure bipolar transistor(HBT)has become the main development direction of high frequency power amplifier because of its good power density,linearity,high frequency characteristics and current driving capability.GaAs HBT power amplifiers are widely used in radar,optical communications,mobile phones and other fields.But at the same time,the high power density on the chip makes the temperature of the circuit working normally is very high,which affects the performance and reliability of the circuit.Therefore,the study of temperature distribution is very important for the design of HBT power amplifier.The temperature distribution of the chip is given.When the circuit simulation and layout design are taken into account,the influence of the temperature distribution is fully considered,and the accuracy of the circuit design can be improved.The main purpose of this paper is to analyze the steady-state temperature of the GaAs HBT power amplifier.The purpose is to accurately calculate the temperature distribution of the chip junction of the RF power amplifier before the flow sheet.In this paper,three widely used methods of temperature analysis are compared.After analyzing the shortcomings of the existing methods,an improved thermal coupling iterative temperature analysis method is proposed.The method is based on the traditional electrothermal coupling iteration,and improves the thermal model and circuit model respectively.(1)improvement point 1: in the process of establishing the thermal model,the thermal model of the active region of the chip is put forward relative to the traditional simple multi-layer structure hypothesis and the whole thermal loading mode.The self heating temperature simulation of the 8 finger power unit Q80 shows that the thermal accuracy of the active region is increased by 14 degrees.(2)improvement point two: Based on the traditional VBIC circuit model,considering that the devices often use parallel multiple fingers in the actual amplifier design,on the basis of the traditional single order thermoelectric network,the relationship between the temperature distribution and the power density and the layout parameters is analyzed with the EDA software,and a distributed VBIC circuit model is proposed.In this model,the interdigital thermal coupling effect of HBT is described by introducing interdigital distributed thermal resistance network,and the expression of model parameters on the layout structure is given.The electrothermal coupling iteration results for power unit Q80 show that the convergence speed of the distributed VBIC model is increased by 30% and the error is increased by more than 20%.Finally,the YP163137 GaAs HBT RF power amplifier chip of Suzhou inno Xun company is used for the simulation and infrared testing of the model.The results show that,compared with the traditional method,the error of the peak temperature of the improved temperature analysis method is reduced by 8,the iterative convergence time is increased by 25%,and the temperature distribution error is reduced by 13.6%.The research results show that the improved electrothermal coupling iteration method proposed in this paper has good accuracy and speed.