Energy-Efficient Fast-Transient Dynamic Reconfigurable Charge Pump for Multi-Channel Electrical Stimulation

An energy-efficient fast-transient dynamic reconfigurable charge pump (CP) is presented for multi-channel electrical stimulation applications. It includes a proposed dynamic reconfigurable CP to improve the overall power saving of the current-controlled stimulator (CCS) system, where individual or integrated controls of multiple CPs are selected by monitoring the CCS channels. For further energy-efficient operation, the stimulation mode-adaptive power on-off scheme is augmented by adopting a low-power two-dimensional frequency modulation (TFM) control and an initial pre-charging diode (IPD) circuit in the CP cores for fast settling performance. A CP prototype is fabricated in a 180-nm CMOS process, and its proposed operations were experimentally verified, achieving an overall more than 80% power-saving effect with maximum 69.8% general power efficiency and fast recovery performance.