出典:Wikipedia
出典:『Wikipedia』 (2011/01/31 15:56 UTC 版)
The heterojunction bipolar transistor (HBT) is an improvement of the bipolar junction transistor (BJT) that can handle signals of very high frequencies up to several hundred GHz. It is common in modern ultrafast circuits, mostly radio-frequency (RF) systems, as well as applications requiring a high power efficiency, such as power amplifiers in cellular phones. The idea of employing a heterojunction is as old as the conventional BJT, dating back to a patent from 1951.