Design And Thermal Analysis Of The Ka-band Power Amplifier Based GaN

This paper studies the design of high-frequency power amplifier based on GaN and thetheory of thermal analysis, explains the necessity of thermal analysis in the process of thedesign of power amplifier. In recent years, the active phased array radar has become the focusof academic research, active phased array radar antenna is composed by T/R modules, eachT/R module has a separated function of receiver and transmitter, any damage to a group ofT/R module will not affect the work of other modules, which greatly improves the stabilityof the radar. Therefore, T/R module determines the overall performance of the radar, firstlywe need improve the performance of the T/R module, and the other hand we want tominimize the volume of the T/R modules, to make the whole radar toward miniaturization.T/R module has the function of receiver and transmitter, its components contain filters,mixers, amplifiers, low-noise amplifier etc. in these parts, this paper focuses on the design ofhigh-frequency power amplifier based on Ka-band, this application uses GaN material whichhas high saturated electron drift velocity, high breakdown voltage, and corrosion resistanceto radiation. To achieve miniaturization, we use the technology of MMIC, this technologynot only can greatly reduce the cost of production, but also improve the stability of theamplifier. We will have another important issue here, the power amplifier is the main sourceof heat in T/R module, the collector junction produces a steady stream, this part of the heatwill affect the work of T/R modules and the overall performance if it can not be releasedeffectively, so it is necessary to do thermal analysis of power amplifier and T/R modules, toensure T/R modules can work within the normal temperature range.Firstly, we design and simulate the power amplifier on35-37GHz, the output power isgreater than34dBm, power added efficiency is greater than4%, a gain higher than9dB, in-band gain flatness is less than0.6dB, and it has reached the original design specifications. Infuture the MMIC chip will be installed to LTCC substrate. So after the MMIC assemblymodel is given, we do thermal simulation analysis find the best cooling assembly model, andthe impact of its thermal performance is mainly the layout of thermal. In order to improvethermal performance further, we simulate several different models, and find the best coolingassembly model. After completing these work, it will provide guidance for the successfulimplementation of post-tape of the MMIC assemble.