Improved SOA in low cost power transistor

Recent theories on second breakdown are reviewed. A simple concept on avalanche injection is proposed. The condition of distributed series resistance on stability factor analysis is discussed. An ingenious Motorola patent to realize this condition with low cost precision is illustrated and results on Power Base^(R) product design shown. Observations confirm the substantial SOA improvement using above design features on the same emitter geometry and chip size. Conventional hot spot was not noted.