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Power Transistor Having Increased Reverse Bias Safe Operating Area

IP.com Disclosure Number: IPCOM000081175D
Original Publication Date: 1974-Apr-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Gillett, JB: AUTHOR

Abstract

An appropriately shaped emitter structure in a power transistor reduces collector current concentration under the center of the emitter, due to the base voltage gradient during turn off. Reducing the collector current concentration increases the reverse bias safe operating area of the power transistor.

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Power Transistor Having Increased Reverse Bias Safe Operating Area

An appropriately shaped emitter structure in a power transistor reduces collector current concentration under the center of the emitter, due to the base voltage gradient during turn off. Reducing the collector current concentration increases the reverse bias safe operating area of the power transistor.

Fig. 1 shows emitter 10 and base 12 topology for a power transistor. The emitter 10 includes an opening or hole 14. Current flow through the emitter is distributed over a greater area by the hole 14. Extending the area of current flow through the emitter reduces the concentration of current under the emitter, which otherwise forms a "hot spot". The extended emitter current flow increases the reverse bias safe operating area.

Fig. 2 shows emitter metallization 16 and base contact 18 for the topology shown in Fig. 1. The emitter metallization 16 is continued over the opening or hole 14, maintaining the same longitudinal voltage drop as in an emitter electrode without an opening or hole. The collector current 20 under the emitter electrodes 10 is distributed over a larger area than that for a single-emitter electrode, thereby increasing the reverse bias safe operating area for the power transistor.

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