Santoro, F.;Kuhn, R.;Gibson, N.;Rasera, N.;Tost, T.;Graeb, H.;Wicht, B.;Brederlow, R. A Hysteretic Buck Converter With 92.1% Maximum Efficiency Designed for Ultra-Low Power and Fast Wake-Up SoC Applications IEEE Journal of Solid-State Circuits 2018 53 6 June 1856-1868