Embedded capacitance in the PCB of switchmode converters

Abstract

It is proposed that one or more capacitance layers are included in the multilayer printed circuit boards of switchmode power supplies. This technology makes it possible to integrate the filter and resonance capacitors of high frequency power electronic converters. In addition, control circuit capacitors can also be included in the PCB making it possible reduce the component count of the circuit assembly. Various capacitive layer technologies are presented that makes it possible to get capacitance of up to 10nF/cm/sup 2/. The capacitance requirements of a typical switch-mode converter are investigated and two case studies are presented. In the first example a ferroelectric ceramic is used and in the second a polymer laminate.