A 4.1W/mm² Peak Power Density and 77% Peak Efficiency Fully Integrated DC-DC Converter based on Electromagnetically Coupled Class-D LC Oscillators and a Resonant LC Flying Impedance in 22nm FDSOI CMOS.

This paper presents a fully integrated DC-DC converter based on electromagnetically coupled class-D LC oscillators. The proposed converter features a hybrid LC flying impedance, ZFLY, which lowers the converter output resistance ROUT by introducing a resonant charge exchange with the output capacitor Co. The improved ROUT provides a peak efficiency of 77% and a peak power density of 4.1W/mm ² , marking a significant improvement with respect the state-of-the-art. The output voltage regulation is obtained with a duty-cycling control scheme that maintains the efficiency loss <2% from 0.003W/mm ² up to 2.1W/mm ² . The proposed DC-DC converter is fabricated in a 22nm FDSOI CMOS process with a total area of 0.33mm ² .