Research On GaN HEMT Large Signal Model For Power Amplifier Design

Since entering the information age,the research of microelectronics has gradually shifted to the third generation of semiconductor materials,such as InP,GaN,SiC,etc.GaN-HEMT has the advantages of high output power and high frequency condition.It is suitable for the design of power devices and high-power integrated circuits.Therefore,it is of great significance to study the analytical model of GaN HEMT devices.Empirical,semi-empirical and semi-physical models are the most studied models.As the length of the channel decreases,the size of GaN-HEMT devices becomes smaller and smaller.At the same time,the self heating effect and trapping effect also need to add a lot of empirical parameters to the model.This will make it difficult to extract parameters from the model,and also lead to non convergence of model simulation.In addition,as the channel length of the device becomes smaller and smaller,the short channel effect will become more and more obvious,and the demand for short channel effect modeling will become more and more important.Therefore,the research of physical based GaN-HEMT large signal model is very important for describing the complex two stage effect of the device and reducing the model parameters.This thesis researches the small-signal equivalent circuit model of the wideband GaN HEMT device with a channel length of 0.1 ?m W-band,the experience-based large-signal model and the improved QPZD large-signal model.The main research contents include:A new GaN HEMT small signal equivalent circuit model and a complete and processing parameter extraction method are proposed.According to the device structure,the influence of high frequency parasitic effect is analyzed,and parasitic parameters are extracted and optimized step by step.The model parameters are avoided to fall into local minimum.The measurement and simulated results of the GaN HEMT device with a channel length of 0.1 ?m show that the average S-parameter error of 1-110 GHz can be reduced within 6%.In addition,the methods of equivalent circuit and parameter extraction and optimization are also applicable to scaling models.The experience-based large-signal model of GaN HEMT is researched and improved.Because the short-channel effect of 0.1 ?m GaN HEMT devices is more serious,the traditional Angelov empirical-based large-signal ? equation often needs to add a lot of empirical parameters.This thesis proposes an ? equation containing only 17 empirical parameters,which greatly reduces the complexity of the model.The QPZD large-signal model of GaN HEMT is researched.Under the influence of short channel effect,the orignal QPZD model is inaccurate in the ? equation.This thesis proposes a new QPZD model.The comparison of the measurement and simulated results of 0.1 ?m process GaN HEMT devices with different channel length sizes show that the new QPZD model can accurately reflect the large signal harmonic characteristics of the device such as output power,efficiency and gain.And the model is applied to the W band power amplifier circuit.The comparison between the measurement results and the simulation results shows that the large signal harmonic verification performance of the model is more accurate when the circuit operating frequency ranges from 92 to 96 GHz.