Internal self-damping optimization in trench power FETs for high-frequency conversion

The impact of the shield resistance (Rsh) on the waveform ringing and system efficiency is assessed in this work for 30V trench power FETs with shielded-gate (TP-FETs). Two different approaches, named distributed and local Rsh, are extensively investigated by experimental and numerical simulation tools. A layout distributed Rsh emerges as the ultimate solution to maximize the self-damping without penalization on the switching power losses or the product cost. The practical implementation of a TP-FET with distributed Rsh in a 12V-to-1.2V buck converter results in one of the best tradeoffs ever reported between overvoltage (<;3.5V) and peak efficiency (~88%) when operating at 1.3MHz.