A reconfigurable 2× / 2.5× / 3× / 4× SC DC-DC regulator for enhancing area and power efficiencies in transcutaneous power transmission

A reconfigurable 2× / 2.5× / 3× / 4× switched-capacitor DC-DC regulator for transcutaneous power transmission is presented in this paper. The proposed power stage enables the regulator to maintain high power efficiencies under different input voltages caused by coupling variations. A fixed on-time regulation scheme is developed to minimize the switching power loss and to achieve small output ripple voltages of the regulator. Implemented in a standard 0.35-μm n-well CMOS process, the proposed regulator delivers a maximum output current of 10 mA and achieves the peak power efficiency of 82%. When the input voltage varies by 1.6 V, the power efficiency of the proposed regulator can be improved by 40% compared to that of the fixed-ratio 4× counterpart. The output ripple reaches 0.5% of the output voltage.