Conclusions and Outlook

Abstract

A fully autonomous integrated interface circuit for piezoelectric harvesters has been presented in this book. By the use of a modified Synchronous Electric Charge Extraction (SECE) technique, the conduction losses within the circuit can be significantly reduced, increasing the total efficiency. Corresponding Pulsed Synchronous Charge Extractor (PSCE) chips demonstrating the superiority compared to standard full-wave rectifier circuits have been been fabricated in a $0.35\,{\upmu \mathrm{{m}}}$ CMOS process. Their transistor level design is presented. The chips have been successfully tested under laboratory conditions, whereas real piezoelectric generators have been used as a power supply. A fully autonomous demonstrator board has been built which allows switching between a commonly used full-wave diode rectifier and the PSCE chip, whereas a flashing light emitting diode (LED) indicates that the PSCE chip is capable of extracting more power compared to the full-wave rectifier. The demonstrator board works properly in combination with a custom made piezoelectric generator from Christoph Eichhorn which is excited with a $5\,{\mathrm{{m}/s^{2}}}$ acceleration amplitude at a frequency of $114\,{\mathrm{{Hz}}}$, resulting in $30\,{\upmu \mathrm{{W}}}$ output power.