Switched Capacitor DC-DC Converter in 65nm CMOS Technology with a Peak Efficiency of 97%

This paper presents a highly efficient switched capacitor (SC) DC-DC converter, which is implemented in a 65nm low power CMOS process to enable SoC integration. The converter supplies a nominal output current of 30mA with an efficiency of 95%. The buck converter operates with a constant input voltage of 1.83V and produces an output voltage of 1.2V. The charge is transported in two phases from the input supply to the output capacitor. Therefore, a network consisting of switches and two so-called flying capacitors are used. This converter is intended to be used in power management units for mobile devices and to substitute complex and expensive inductor based DC-DC converters. A test chip was designed in collaboration with Infineon Technologies Austria AG. The measurement results are presented and give for an output current of 10mA a peak efficiency of 97%.