An analytical model tailored for analyzing the fast turn-off transient characteristics of LIGBT/LDMOS

accounting for the transient charge-distribution in the wide quasi-neutral base （QNB） of the pnp bipolar-junction transistor （BJT） and the back-injection effect. is proposed in the paper. The charge-control equation including the extraction of the excess carrier out of the QNB of the pnp BJT by the LDMOS transistor is solved and the normalized turn-off transient current is then obtained. The results give the relationships of the turn-off time from the analytical modeling with the device parameters of LIGBT/LDMOS

e.g. the ratio of width between p+ of LIGBT and n+ of LDMOS

high-injection carrier lifetime

back-injection current density and width of drift region. The modeling methodology is also applicable to the mixed CIGBT （Complementary IGBT） and others.