A New Approach to Prevent the Burnout Under Mismatching Load Conditions in High Power HBT

This paper describes a burnout mechanism in high power KBT under mismatching load conditions. Experimental and analytical investigations reveal that the burnout of the HBT is caused by a large amount of base current resulting from avalanche breakdown in a collector-base junction, especially in the case of constant base voltage drive usually employed in high power operation. Based on the investigation, an active feedback circuit is newly proposed to prevent the catastrophic failure, and then the effectiveness of the circuit was successfully confirmed by simulation and experiments.