A Power-Enhanced Active Rectifier with Offset-Controlled Comparator for Self-Powered PEH Systems

摘要

In this paper, a power-enhanced active rectifier with high precision of current detection for piezoelectric energy harvesting (PEH) system is presented. A traditional two-stage active rectifier is adopted, which includes a first-stage negative voltage converter and an active diode. A comparator with offset control technique is proposed; thus the input-referred offset voltage of the proposed comparator can be less than 1 mV. The current detected accuracy of the proposed offset-controlled comparator (OCC) is improved by more than 10 times over a traditional comparator. Output oscillations of the OCC are dramatically reduced attributing to the high precision of current detection. In addition, the OCC is also able to prevent the reverse leakage current. The design is implemented in an SMIC 0.18 mu m standard CMOS technology with a chip area of 0.22 mm(2). The measurement results show that the maximum output power, power conversion efficiency and figure of merit are 23.3 mu W, 90%, and 0.9, respectively, when the open-circuit voltage is 2.4 V. The proposed rectifier can be self-powered without the additional external supply.