No abstract

This paper presents a two-stage synchronous rectifier interface circuit for piezoelectric energy harvesting (PEH) system. The proposed rectifier includes a first-stage negative voltage converter, a second-stage adaptive on-resistance active diode, and combines a precise switch-on-time controlled P-SSHI circuit. The traditional active two-stage synchronous rectifier has lower current detection accuracy and hardly achieves high efficiency rectification over a wide input current range. An adaptive on-resistance active diode (AOR active diode) is proposed to replace the traditional active diode to achieve higher current zero-crossing detection accuracy, improve the input current range and the output power of the rectifier. The proposed diode allows the rectifier to maintain high rectification efficiency over a wider input current range. Further, a parallel synchronized switch harvesting on inductor (P-SSHI) with precise switch-on-time controlled circuit is proposed to achieve higher voltage flipping efficiency and improve the power extraction capability of the rectifier. By using the AOR active diode and the P-SSHI with precise switch-on-time controlled circuit, a good performance improvement has been achieved for the proposed interface circuit. The design is fabricated in an SMIC 0.35[Formula: see text][Formula: see text]m standard CMOS technology with a die size of [Formula: see text][Formula: see text]mm2. The simulation results indicate that the proposed circuit achieves more than 80% power converting efficiency and its peak efficiency is 85%. The current zero-crossing detection accuracy of the proposed AOR active diode is less than 10[Formula: see text][Formula: see text]A. The proposed PEH interface circuit extracts up to 2.81 times more output power compared with a traditional rectifier. The voltage flipping efficiency of the P-SSHI circuit is up to 90%, which can effectively improve the power extraction capability of the rectifier. Moreover, the proposed circuit can be self-powered and cold started up.