Origin of Anomalous <inline-formula> <tex-math notation="LaTeX">$C_{\mathrm {OSS}}$ </tex-math></inline-formula> Hysteresis in Resonant Converters With Superjunction FETs

Abstract

Output capacitance (C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OSS</sub> ) hysteresis has recently been discovered as a new source of power loss in resonant converters with advanced superjunction (SJ) FETs. This brief unveils the physical mechanism responsible for C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OSS</sub> hysteresis by means of mixed-mode simulations. A new physical effect, based on stranded charges, is observed in the SJ-FETs processed by multi-implant multiepitaxy with small cell pitch. The alternative trench-filling epitaxial growth is a process suitable to address the resonant converters due to its inherent immunity to the C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OSS</sub> hysteresis.