A Fully Integrated Split-Electrode SSHC Rectifier for Piezoelectric Energy Harvesting

In order to efficiently extract power from piezoelectric vibration energy harvesters, various active rectifiers have been proposed in the past decade, which include synchronized switch harvesting on inductor (SSHI), synchronous electric charge extraction (SECE), and so on. Although reported active rectifiers show good performance improvements compared to full-bridge rectifiers (FBRs), large off-chip inductors are typically required and the system volume is inevitably increased as a result, counter to the requirement for system miniaturization. In this paper, a fully integrated split-electrode synchronized switch harvesting on capacitors (SSHC) rectifier is proposed, which achieves significant performance enhancement without employing any off-chip components. The proposed circuit is designed and fabricated in a 0.18-
$\mu \text{m}$
CMOS process and it is co-integrated with a custom microelectromechanical systems (MEMS) piezoelectric transducer with its electrode layer equally split into four regions. The measured results show that the proposed rectifier can provide up to 8.2
$\times $
and 5.2
$\times $
boost, using on-chip and off-chip diodes, respectively, in harvested power compared to an FBR under low excitation levels and the peak rectified output power achieves 186
$\mu \text{W}$
.