Research On Drive Circuit Design And Stability Analysis Of Discrete Enhanced-Mode GaN Circuit

Gallium Nitride(GaN)semiconductor devices have excellent electrical properties and great application advantages than Silicon(Silcon,Si)semiconductor devices.In practical applications,the full play of the excellent performance of GaN devices is closely related to the design of gate drive circuit.But the design of gate drive circuit is faced with the challenges of low threshold voltage and small safe range of gate voltage.The drive circuit for Si MOSFET is not suitable for GaN transistors.Therefore,this paper will design a suitable gate drive circuit for enhanced-mode(E-mode)GaN devices,and then use the negative conductance model to analyze the stability of GaN-based circuits.Firstly,the device structure and switching characteristics of 600 V E-mode GaN transistor are studied.A 600V E-mode GaN device Hybrid Drain Gate Injection Transisotr(HDGIT)is studied.The mechanism of its normally-off and current collapse suppression is analyzed.It is clear that it is different from MOSFET in the switching process.A double pulse test platform is established to test the switching performance of the transistor.The test results are compared with another 650V E-mode GaN transistor GS66508P.Secondly,the drive circuit suitable for E-mode GaN transistor is designed.According to the characteristics of parasitic diodes in gate source of GaN HDGIT,RC-type drive circuit is designed by using gate driver UCC27511 and gate driver AN34092B with built-in constant current source.The working mechanism of the two drive circuits is analyzed,and the corresponding dual-pulse test platform is built.The switch performance under different current levels is tested and compared.Two optimum designs for E-mode GaN devices without parasitic diodes are proposed,and the feasibility of the optimum design is verified by simulation and experiment.Finally,the basic theory stability criteria of two oscillators and negative resistance oscillator theory are introduced.It is clear that the negative conductance model is more appropriate to judge the stability of GaN-based circuits.Secondly,based on the GaN HDGIT dual-pulse test platform,the negative conductance model of the test circuit is established,and then the stability of the GaN-based circuit is judged based on the stability criterion of the negative conductance model.The circuit stability of GaN HDGIT device PGA26E07BA at different voltage levels is analyzed.The accuracy of the proposed model is verified by the experimental results of the double pulse test platform.