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Journal of Sensors
Volume 2010, Article ID 349389, 6 pages
http://dx.doi.org/10.1155/2010/349389
Research Article

Photovoltaic Energy Harvester with Power Management System

Department of Electrical Engineering, University of Pavia, 27100 Pavia, Italy

Received 27 July 2010; Accepted 25 October 2010

Academic Editor: P. Siciliano

Copyright © 2010 M. Ferri et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We present a photovoltaic energy harvester, realized in 0.35-μm CMOS technology. The proposed system collects light energy from the environment, by means of 2-mm2 on-chip integrated microsolar cells, and accumulates it in an external capacitor. While the capacitor is charging, the load is disconnected. When the energy in the external capacitor is enough to operate the load for a predefined time slot, the load is connected to the capacitor by a power management circuit. The choice of the value of the capacitance determines the operating time slot for the load. The proposed solution is suitable for discrete-time-regime applications, such as sensor network nodes, or, in general, systems that require power supply periodically for short time slots. The power management circuit includes a charge pump, a comparator, a level shifter, and a linear voltage regulator. The whole system has been extensively simulated, integrated, and experimentally characterized.