These mandated requirements have evolved over the years, with the most stringent requirements introduced in 2001, with wave shape requirements for domestic equipment in the 75 W to 600 W range. Various solutions exist from Infineon, including single stage approaches incorporating a charge pump circuit which while having some waveform distortion meet the requirements of 61000-3-2-1, or two stage SMPS approaches with a PFC boost converter active filter producing very low harmonic content.