الفهرس 
Multi-source energy harvesting system for wireless sensor networks
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Abstract
In this thesis, a multi-input multi-output energy harvesting system that combines piezoelectric and photovoltaic sources is presented. It is a dual path system that uses a single inductor for both boost and buck converter. The boost converter, working in the discontinuous conduction mode (DCM), utilizes an active diode (AD) technique to avoid negative current Àowing in the inductor and a control technique that allows supplying dual output voltage levels with su{u01A5}cient power. The AD is implemented using a level-sensitive clocked comparator that is driven by the system clock while consuming 350nA only. The system undergoes four states of operation to achieve two voltage levels at the output of 1.2V and 3V. The system clock is chosen as a compromise between required speed of the comparator, switching losses, and size of external inductor. Switch sizing programmability and digital control for the loads connected to the energy harvesting system is introduced to achieve better e{u01A5}ciency and to make use of the transducers all the time. Post-layout simulation results show an overall e{u01A5}ciency of 92% for an input power of 1.2 mW while providing two outputs at 1.2V and 3V in 130nm CMOS technology