Device Modeling And GaN Power Amplifier Research Based On ASM-HEMT Model

The third generation of semiconductor material GaN is the core representative of wide band gap semiconductor materials.Because of its wide band gap width,high electron mobility and electron saturation speed,the semiconductor devices manufactured based on GaN still have excellent performance in high temperature and high pressure environment.Due to spontaneous polarization and piezoelectric polarization,undoped AlGaN/GaN heterojunction materials produce high concentration of 2DEG at the interface and exhibit excellent device performance.High electron mobility transistor(AGaN/GaN HEMT)devices based on AlGaN/GaN heterostructure have excellent microwave and power characteristics.Makes it in the telecommunications and communication,quick charge equipment,server power supply,electric cars,has been widely applied in various fields,such as the growing popularity of the GaN chargers in recent years,in particular,for many technology companies to see the broad market prospect,and began to GaN materials,devices and circuit in further research,this article from the device performance analysis,device modeling,Starting with the application of circuit simulation,a series of research work is done on AlGaN/GaN HEMT devices,including:1)DC device modeling of AlGaN/GaN HEMTFour AlGaN/GaN HEMT devices were fabricated.The size of the device A was 0.35um in length,20×2um in width,and 2um in source and drain spacing.The size of device B is 0.25um grid length,20×2um grid width,and the spacing between grid source and grid drain is lum.The size of device C is grid length 0.1um,grid width 20×2um,grid source and grid drain spacing lum.The size of device D is 0.03um grid length,40×2um grid width,and the spacing between grid source and grid drain is lum.The dc characteristics,frequency characteristics and power amplification characteristics of these devices were tested.The mature commercial software BsimProPLUS was used to conduct device modeling and model parameter extraction for DC characteristics of the prepared devices.Compared with the test results,the ESTABLISHED DC characteristic model obtained better model accuracy.Then,the four extracted DC models were analyzed at the circuit level as standard device DC models.ADS software was used to simulate the DC characteristics of the four extracted DC models respectively.The obtained simulation results were found to be in good consistency with the test results,which further verified the accuracy of extracted DC models.2)AlGaN/GaN HEMT small signal model establishmentFor preparation of four devices,using ADS software for the construction of the small signal equivalent circuit model and simulation,respectively,using the method of ice and hot field method to model parameter extraction of S parameters,get the parasitic capacitance and parasitic inductance and parasitic resistance,and analysis to extract the intrinsic parameters of the device,get a complete small signal S parameter model,Then use ADS to build AlGaN/GaN HEMT nonlinear communication model,and then extracted four small signal S parameter model of the device is embedded into the circuit simulation of the static working point,the simulation results compared with S parameter test result has higher fitting precision,illustrate the correctness of the extraction of the small signal S parameter model.3)Application and linearity of AlGaN/GaN HEMT devices in power amplifiersIn the previous section to extract nonlinear dc model and nonlinear model on the basis of communication,through the fitting of nonlinear ac component of the device set up four large signal equivalent circuit model,and then through the ADS software structures,impedance matching circuit,the conjugate matching the input and output impedance value,The input and output impedance and the maximum effective power gain obtained by theoretical calculation are compared,further analyzing the device performance of power amplifier,It mainly includes power gain,linearity and additional effective power gain(PAE).The power amplifier performance of the devices prepared at different device sizes is studied in depth,with emphasis on the relationship between the power amplifier performance of the four devices and the parameters such as broken conductance GM extracted from device modeling.The results show that the longer the gate length and width,the smaller the gate source spacing,the gentler the collapse conductance variation,and the better the linearity of the power amplifier.