Enhancing Efficiency in Piezoelectric Energy Harvesting: Collaborative-Flip Synchronized Switch Harvesting on Capacitors Rectifier and Multioutput DC-DC Converters Utilizing Shared Capacitors

This article proposes a novel collaborative-flip synchronized switch harvesting on capacitors (CF-SSHCs) rectifier and multioutput synchronous dc-dc converters with shared capacitors. Compared to the traditional SSHC, our CF-SSHC rectifier can increase the number of flipping phases, potentially enhancing the flipping efficiency and output power under specific conditions where C_{\text{FLY}} is close to C_P . The synchronous dc-dc converters reuse the flying capacitors to achieve a high maximum output power improving rate (MOPIR) over a limited input power range and provide multiple outputs. This work achieves an advanced number of flipping phases in capacitor-based rectifier interface technology and explores multiple-input multiple-output configurations, evaluating the system's performance under periodic and shock conditions for the first time. The system's adaptability to various piezoelectric transducer (PT) array configurations is validated, highlighting its potential for Internet of Things (IoT) networks. The design is fabricated in standard 0.18- \mu m CMOS. Measurement results demonstrate that the voltage flipping efficiency of up to 83% is achieved. Compared with full-bridge rectifier (FBR), the MOPIR can be increased to 5.06 \times and 4.78 \times under off-resonance and on-resonance excitation, respectively. It can also achieve a 2.14 \times power enhancement under shock excitation. Additionally, when the input power P_{\text{IN\_FBR}} is in the range of 1.42-28.4 \mu W, the MOPIR of the proposed system is always greater than 4.