High power static induction transistor

SIT is usually constructed as vertical and multi-channel structure, resulting in a realization of large area device, i.e., high current operation, where temperature dependence of SIT enhances its large area characteristics without accompanying thermal runaway, because the temperature coefficient of drain current is negative in high current region. An introduction of high resistivity region between gate and drain increases its breakdown voltage and decreases gate to drain capacitance, resulting in an improvement of handling power and frequency characteristic. High power SIT having a cell size of 12.8 × 12.8 mm²has been fabricated to obtain killowatts operation in radio frequencies, which is characterized by burried gate and extremely long stripe channel structure. Gate to drain breakdown voltage is higher than at least 800 V and maximum drain current is up to 60 A. Ultrasonic wave generator using two high power SITs in push-pull configuration exhibits 3 KW output operation at an efficiency higher than 85 % at a frequency of 28 KHz, where the driving power of SIT is Iess than 5W. 100 KHz switching regulator has been realized and exhibits 300 W output at an efficiency of 70 %. This efficiency is limited by properties of ferrite core. SIT has been confirmed experimentally very promising to high power transisters in high frequencies.