Qadier I.  Jilluh, Allenn C.  Lowaton, 
    A Piezoelectric Energy Harvesting Interface Circuit Using Negative Voltage Converter,
    Journal of Engineering and Applied Sciences,
    Volume 11,Issue 10,
    2016,
    Pages 2249-2254,
    ISSN 1816-949x,
    jeasci.2016.2249.2254,
    (https://makhillpublications.co/view-article.php?doi=jeasci.2016.2249.2254)
    Abstract: This study presents a piezoelectric energy harvesting system electric interface which includes two main sections; a rectifier and a voltage regulator. The negative voltage converter, an improved version of the full bridge rectifier coupled with an active diode implementation is used to convert the extracted AC power from the transducer. The simulation results shows that the power extraction efficiency of the proposed rectifier is 2.2 times that of a conventional full bridge rectifier and >82% of power conversion can be achieve. To complete the harvesting system a low powered DC-DC Buck converter is used to regulate the power extracted by the rectifier to run a wireless sensor node operating at 1.5 V voltage and 2 mA current. The buck converter has a load regulation measured at 0.18 mV/mA and a line regulation of 0.18 mV/V. The buck converter has a maximum efficiency of 84% with 1% voltage ripple. The die size for the overall layout is 1008x1008 μm including pad.
    Keywords: negative voltage converter;Energy harvesting;piezoelectric;efficiency;negative voltage