A Criterion for Base Punch-Through in Bipolar Transis for Design

A theoretical analysis of base punchthrough problem of transistors is presented. A general formula of punch-through voltage for transistors with arbitrary doping profile is derived. Particularly, a crterion for base punch-through not to occur before collector junction avalanche breakdown is obtained. This result, which has been confirmed experimelally, can be used as a principle in bipolar transistor design.