Research And Design Of High-Efficiency And High-linearity RF Power Amplifier Based On GaAs HBT Technology

In LTE small cell applications,the RF power amplifier is the most energy-consuming component in the transmitter.In addition to meeting the strict linear specifications of LTE,it is also necessary to increase the efficiency at the power back off point as much as possible.Small cell,although not relying on portable batteries for power supply,are often deployed intensively.Therefore,the low-efficient means a large amount of energy loss.Achieving high-efficient and high-linear RF power amplifiers is significant.By using the ideal strong nonlinear model,this paper analyzes the significance of the conduction angle reduction in practical engineering application.Then,by comparing the advantages and disadvantages of HBT under various process technology,this paper expounds the reasons for using GaAs HBT as the process technology of this design.By using small signal model and large signal model,the influence of nonlinear capacitance effect of HBT on AM-PM is analyzed.Different from the traditional empirical design method,this paper puts forward a more accurate design flow for determining the die area and bias point of the power stage in view of the requirements of the module for the efficiency of 1dB compression point and power back off point.At the same time,in the physical implementation of the module,the use of a wide range of tuning,but at the same time can be fine-tuned output matching network structure,improve the success rate of the first design.Finally,according to the specification of LTE system,this paper designs an high-efficiency and high-linearity RF power amplifier module with a frequency band of 925 MHz to 960 MHz based on GaAs HBT process.The module is realized by single chip integration combined with substrate material,and the high-efficiency power amplifier module which can meet the strict linear specification of LTE system is realized in smaller size by using two-stage amplifier and self-adaptive bias.The final test results of the module show that the output power of the 1dB compression point is 32.3dBm,which provide 31.6dB power gain.When the output power is backed off,the power added efficiency is as high as 17.4%,ACPR<-48.6dBc.The good performance of the power amplifier test shows the correctness and feasibility of the theory and design method.