Research On Large-signal Model Of Surface Potential-based GaN HEMT

With the arrival of the 5G era,the first and second generation semiconductor devices represented by Si and Ga As materials have been unable to meet the application requirements of the current high-power scenarios.However,the third generation wide-bandgap semiconductor led by GaN has gradually revealed its unique advantages.GaN HEMT devices are the most promising RF power devices with high power density and high frequency characteristics.In the circuit design process,accurate device model can greatly shorten the development cycle and reduce the cost.Due to the complex self-heating and trapping effects of GaN HEMT devices,it is difficult to accurately model their large signal characteristics.In this paper,a GaN HEMT current and charge model is developed and improved based on the core equation of ASM-HEMT model.The main research contents are as follows:(1)The advantages of GaN materials,fabrication materials and physical structure of GaN HEMT devices are studied,and the working principle of GaN HEMT devices is introduced.Pulse and load pull test of GaN HEMT are studied based on RF on-chip testing technology.A complete test scheme for GaN HEMT device modeling is presented.(2)The core surface potential equation of the original ASM-HEMT model is derived.Starting with the basic physical effects of GaN HEMT devices,the modeling method of GaN HEMT devices is described.Based on the parameter fitting experiment,the shortcomings of ASM model in GaN HEMT device modeling are analyzed.It provides theoretical support for the establishment of improved surface potential-based GaN HEMT large signal model.(3)An improved GaN HEMT large signal model is developed based on the test data of a domestic 0.25?m GaN HEMT device.The gate current,drain current and capacitance models are improved.The self-heating effect is characterized by pulse test method,and the trapping effect is characterized by empirical model.(4)Based on the proposed GaN HEMT device model,a 0.25?m GaN HEMT device size scaling model was established to meet the requirements of circuit design for size scaling model.At the device level and circuit level(c-band power amplifier circuit with 10 components),the small signal characteristic and power characteristic accuracy of the dimensional scaling model are verified.The results show that the surface-potential-based GaN HEMT device model proposed in this paper has good accuracy,convergence,and flexible scalability.