Harvesting ambient vibration energy through piezoelectric means is a popular energy harvesting technique which can potentially supply 10-100's of [mu]W of available power. One of the main limitations of existing piezoelectric harvesters is in their interface circuitry. In this paper, a bias-flip rectifier circuit that can improve the power extraction capability from piezoelectric harvesters over conventional full-bridge rectifiers and voltage doublers by greater than 4X is implemented in a 0.35 [mu]m CMOS process. An efficient control circuit to regulate the output voltage of the rectifier and recharge a storage capacitor is presented. The inductor used within the bias-flip rectifier is shared efficiently with a multitude of switching DC-DC converters within the system reducing the overall component count.
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