An ultra‐high‐voltage high‐speed switching power transistor with new fine emitter structure

Along with the trend toward smaller size and lower energy consumption in electronic equipment, the dc stabilized power supply has been changed from the series dropping to the switching version, which tan he made more compact and light with high efficiency. the switching frequency in these efforts has increased with each year. Component parts are required for performance in higher frequency regions and it is also hoped that switching transistors will be improved in terms of high speed and large safe operating area. High‐speed switching and large safe operating area have hitherto progressed in a trade‐off relation. This was overcome by decreasing the base resistance via S‐parameter analysis. A newly developed fine emitter structure and oxide planar structure have led to creation of an excellent switching power transistor possessing ultra‐high voltage (1200 V), high‐speed switching characteristics (rise time t r = 200 ns, storage time t s t g 2500 nsec, fall time t f = 70 nsec), and large safe operating area (secondary breakdown onset current I sb = 8 A, collector * emitter clamp voltage VCEX(clamp) = 90 V).