October 20, 2014

OnSemi MMBT2222A - npn BJT transistor : weekend die-shot

Die size 343x343 µm. Comparing to NXP BC847B die area is 1.5x larger (0.118 vs 0.076mm²), but maximum continuous collector current is 6 times higher (600mA vs 100mA, SOT-23 in both cases). This huge increase in current per transistor area is achieved by shunting thin (=high-resistance) base layer with metal. High resistance of base layer is the limiting factor for maximum collector current in BC847B.