考虑非线性结电容的SiC BJT模型改进

Improved Model for SiC BJT Considering Nonlinear Junction Capacitances

碳化硅(SiC)双极结型晶体管(BJT)因具有低导通电阻、高开关速度以及低温度依赖性等优势成为功率开关应用的一个可行器件,其动态特性主要取决于P/N结中可控硅形成的内部电容,因此建立考虑基极-发射极结电容和基极-集电极结电容的SiC BJT行为模型对SiC BJT功率器件的应用具有重要意义.本文提出了一种考虑非线性结电容的SiC BJT的改进模型,该模型利用受控源对SiC BJT内部结电容进行建模,解决了结电容的非线性以及仿真不收敛等问题.利用仿真软件PSpice对该模型进行了仿真,并与实验得到的直流特性及开关特性进行了对比,验证了模型的有效性.

Silicon carbide(SiC)bipolar junction transistor(BJT)is one of the candidates for power switching applications for its low specific on-resistance,fast switching speed and low-temperature dependence.Its dynamic characteristics are mainly determined by the internal capacitances which are formed by the space charge region in the p/n junctions.Therefore,a model considering the internal capacitances for SiC BJT needs to be proposed,which is of great significance for the application of SiC BJT power devices.In this paper,an improved model for SiC BJT considering nonlinear junction capacitances is proposed,in which the controlled source is used to model the internal junction capacitance and through which the nonlinearity of junction capacitance and the non convergence of simulation are solved.The dc and switching characteristics are simulated and compared with the experimental results.The close agreement between simulated and experimental results confirms the validity of the improved model.This work can provide some guidance for the applications of SiC BJT power devices.