A 2-Mode Reconfigurable SSHI Rectifier with 3.2X Lower Cold-Start Requirement for Piezoelectric Energy Harvesting*

Abstract

Synchronized switch harvesting on inductor (SSHI) rectifier has been verified as an efficient active rectifier to harvest kinetic energy in piezoelectric energy harvesting (PEH) system. Compared with passive rectifiers, active rectifiers including SSHI rectifier require a stable power supply to drive switches. However, when the system starts from the cold state, the required power supply is not available at first. For the active rectifiers, the active circuits work as a typical full bridge rectifier (FBR) until the stable power supply is built up. Unfortunately, a FBR cannot build up a stable power supply when the input open circuit voltage VOC is lower than the required power supply, resulting in disabled active rectifiers. This paper proposes a 2-mode reconfigurable SSHI rectifier design for low input VOC. By this method, the requirement for the input VOC is 3.2X lower than a FBR. The proposed system is designed in a 0.18µm process and post-layout simulations verify the cold start-up process under low VOC voltage.