Temperature Characteristics Of Impedance Matching In GaN Microwave Power Amplifier

Microwave power amplifiers are widely used in many fields,such as mobile communication base stations,radars,satellite communications,aerospace and so on.The third-generation semiconductor material GaN plays an indispensable role in the design of microwave power amplifiers due to its wide band gap,high breakdown field,high electron saturation velocity,high thermal conductivity,and stable chemical properties.However,Al GaN/GaN heterojunction high electron mobility transistors(HEMT)often work under higher temperature and higher power,the temperature characteristics and reliability of the device will be important issues to consider.In the design process of microwave power amplifier,input and output matching circuits are the most critical part to design.This thesis presents a type of printing microstrip lines on a flexible substrate as matching component.The matching circuit was designed by two methods,discrete capacitance and inductance matching and inkjet printed microstrip line matching.Based on these designs,the temperature characteristics of impedance matching were studied in detail.Finally,a 5.3?5.9GHz power amplifier meeting the specification was designed.The main research contents are as follows:1.When using inkjet printed microstrip lines as matching components,the thesis propose to use tapered microstrip lines with segmented grading or continuous grading to keep the characteristic impedance of the transmission line at the specific impedance of50 Ohms.Simulation verified the feasibility of the tapered transmission line.TDR simulation was used to simulate the impedance of different types of transmission lines,time domain and S-parameter simulations done on tapered printed microstrip lines of different slopes and different lengths verified that the tapered printed microstrip line could be used as interconnect for heterogeneous integration of semiconductor chips and printed electronic devices on flexible substrate.2.Cree's CGHV60040D GaN HEMT microwave power amplification chip was chosen to investigate the temperature characteristics.The chip was scanned by DC simulation to determine the static operating point.The bias circuit was designed and stability was analyzed.Load pull and source pull simulations were carried out to determine the load impedance and source impedance of the power amplifier at the temperatures between-70°C and 150°C with an interval of 20°C under 5.3?5.9GHz.The effect of temperature change on the load impedance and source impedance of the power amplifier was investigated.The input and output matching circuit of the amplifier is designed in two ways:discrete capacitor and inductor,and printing microstrip lines printed on flexible substrates.Their temperature behaviors were studied in detail.3.A 5.3?5.9GHz microwave power amplifier was designed.The input and output matching circuits were designed by two methods:capacitor-inductor matching and printed microstrip line matching.Small signal and large signal simulations were done to ensure that under the two matching methods the S₂₁of the amplifier is greater than10d B,S₁₁and S₂₂less than-10d B,the power gain peak value greater than 9d B,and the peak saturation output greater than 45d Bm,and the peak efficiency greater than 40%,respectively.The simulation results proved that the performance of the amplifiers designed by two matching methods reached the requirements.