Start-up Solutions for Ultra-low Power RF Harvesting Scenarios

This paper is an overview of important results obtained by our research group in the field of computer-aided design of highly efficient RF energy harvesters. Particular attention is devoted to start-up strategies for ultra-low power scenarios: an integrated DC-DC converter, with start-up and maximum power point tracking functionalities, as actual load of the rectenna, shows a fully autonomous operation; a dual-branch rectenna with switched-load rectifiers significantly reduces the available RF power levels able to wake-up the system, despite of the discrete components employed. The obtained performance demonstrate, both for off-the-shelf discrete solutions and customized integrated ones, that a rigorous design approach is mandatory, especially when extremely low power budget are involved.