| Scaling of electronics has enabled an increasingly diverse range of products and applications to be realized. Sensors have especially benefited from this trend, enabling them to be designed to be unobtrusive and possible to place in harsh or difficult to reach locations, which previous generations of sensors may not have been able to do. This scaling has introduced a new set of challenges for designers to overcome. However, one major drawback of scaling is the lack of available energy-dense storage. There are two methods to work around this issue, design an efficient energy harvesting scheme, or design a sensor which can operate on limited power budgets. This work will focus on both mentioned methods. First, a circuit structure will be presented to address the limited power budget. These circuit structures will be capable of operating directly from a harvested RF source, without any rectification, and at voltages below the threshold voltage of the transistors. These structures will be demonstrated for a wide range of supply frequencies from 13:57MHz to 2:4 GHz, with voltages as low as 83mVRMS. Second, an energy harvesting and packaging scheme will be introduced to address the issues with packaging antennas into a millimeter scale sensor. These antennas will be built to provide an omnidirectional coverage for RF energy harvesting, which will allow the sensors to rotate and still be functional. This scheme will be realized as a true three-dimensional antenna-in- package structure, with the antennas built directly into the sensor packaging. These structures will be demonstrated from 5mm x 5mm x 5mm to 3mm x 3mm x 3mm cubes, and show an improvement of 21:99 dB in the energy harvesting link over the rotation of such a sensor. |
