Fully integrated capacitive converter with all digital ripple mitigation

Abstract

This paper presents an adaptive all digital ripple mitigation technique for fully integrated capacitive converters. Ripple control is achieved using a two pronged approach where coarse ripple control is achieved by varying the size of the bucket capacitance and fine control is achieved by charge/discharge time modulation of the bucket capacitors used to transfer the charge between the input and output. A dual loop control was used to achieve regulation and ripple control. The fully-integrated converter was implemented in IBM's 130nm CMOS. Enabling ripple mitigation, reduces the measured ripple by 65% for a load of 0.4V and 2mA without significantly impacting the converter core efficiency.