Reconfigurable DC/DC converter for software-defined energy harvesting

In the context of the Internet of Things, wireless sensor nodes are implemented as system-on-chip containing a power management unit, sensors, signal processors, and wireless transceivers. To be energy autonomous, they are supplied with an energy harvester through a converter. The aim of this master thesis is to regulate a SC DC-DC converter output voltage around 0.5 V for an input range of 0.140 - 0.280 V. We have designed a reconfigurable SC DC-DC converter because its conversion rate can be changed according to the input voltage. The converter is adapted from a previous work at UCL which was designed to reach 0.5 V for an input voltage of 0.140 V. A controller regulates the voltage based on Constant On-Time scheme. A maximum power point tracking algorithm determines the efficient configuration by sensing the output voltage from the regulation part. Hence the current sensor is avoided. The controller is composed of analog and digital elements. We simulate the analog part with ELDO in Spice then we integrate it to the digital part with QUESTA in Verilog-AMS. The digital part is tested at the behavioural level. The Energy harvester PMU regulates the output voltage at 0.5 V for an input range of 0.140 - 0.280 V. An overall efficiency of 37.7% is reached for an input power range of 5.2 - 9.4 µW. It can provide a maximum output power of 2.84 µW for an input voltage of 0.28 V.