2. Control characteristics of bipolar transistors and GTO blocking thyristors

The first power transistors were bipolar, and reached technological maturity in the late 1970s, when a better understanding of their complex behavior led to significant improvements. Until then, they shared the market for power semiconductor components with thyristors. Then, gradually and successively, MOSFETs and IGBTs dethroned them from their fields of application. At the beginning of the 21st century, they now occupy only a few niches. In particular, they can be found in "consumer" applications such as electronic ballasts for powering fluorescent or halogen tubes, or in cathode displays (TVs, video monitors), which are themselves in decline. It might therefore seem pointless to deal with them in detail. But in fact, many of the problems they raise can be found in GTO thyristors (Gate turn-Off Thyristor), which look more like very large bipolar transistors than thyristors. That's why...