A miniature and high-efficiency interface circuit based on parallel synchronous switch harvesting on capacitors (P-SSHC) for piezoelectric energy harvesting (PEH) is proposed in this paper. This interface circuit consists of a two-stage synchronous rectifier and the P-SSHC circuit. The two-stage synchronous rectifier, composed of a negative voltage converter (NVC) and an active diode (AD), achieves higher efficiency compared with the full-bridge rectifier (FBR). In addition, the two-stage synchronous rectifier detects the zero-crossing moment of the input current; therefore, an extra current zero-crossing detection circuit is eliminated, which simplifies the structure of the interface circuit, reduces power consumption and improves peak converting efficiency. The P-SSHC circuit aims to improve the power extraction capability of the rectifier. The P-SSHC achieves considerable voltage flipping efficiency with very small volume compared to the parallel synchronized switch harvesting on inductor (P-SSHI), which is more suitable for volume sensitive applications. The proposed interface circuit is designed in SMIC 0.35[Formula: see text][Formula: see text]m CMOS process. Simulation results show that it achieves a [Formula: see text] output power improvement compared with FBR for the case of a 3.4[Formula: see text]V open-circuit voltage, the voltage flipping efficiency is as high as 83.6% and the peak power converting efficiency is up to 91.5%. The overall volume of the capacitors used in this paper is only 0.6[Formula: see text]mm3, which is much smaller than the inductor used by conventional P-SSHI interface circuit.
