A new wide SOA DC-EST structure with diode diverter

Abstract

A novel emitter-switched thyristor (EST) structure with diode diverter is introduced to obtain superior current saturation characteristics with excellent forward bias SOA (FBSOA) without compromising the on-state voltage drop. The new structure comprises a diode diverter connected to the P-base region of the DC-EST. At low current densities, the structure operates like a floating P-base DC-EST with a low forward voltage drop. At higher current densities, the diode diverter diverts the hole current to the cathode, reducing the parasitic thyristor latch-up susceptibility. Extensive numerical simulations are presented to analyze the physics of operation of this novel structure. Experimental results are reported, confirming the superior characteristics observed through simulations. Current saturation control was observed by varying the diode knee voltage. The DC-EST with diode diverter is shown to have a square FBSOA. The saturation current density was lowered by a factor of 1.5/spl times/, which is desirable to achieve good short circuit SOA (SCSOA). The diode diverter concept is shown to be especially advantageous in the high voltage (4 kV) regime.