RF Integrated Circuits for Energy Autonomous Sensor Nodes

The exponential growth in the semiconductor industry has enabled computers to pervade our everyday lives and as we move forward many of these computers will have form factors much smaller than a typical laptop or smartphone. Sensor nodes will soon be deployed ubiquitously, capable of capturing information of their surrounding environment. The next step is to connect all these different nodes together into an entire interconnected system. This "Internet of Things" (IoT) vision has incredible potential to change our lives commercially, socially, and personally. The backbone of IoT is the wireless sensor node, many of which will operate under very rigorous energy constraints with small batteries or no batteries at all. It has been shown that in sensor nodes, radio communication is one of the biggest bottlenecks to ultra-low power design.
This research explores ways to reduce energy consumption in radios for wireless sensor networks, allowing them to run off harvested energy, while maintaining many qualities that will enable them to function in a real world, multi-user environment. Three different prototypes have been designed demonstrating these techniques. The first is a sensitivity-reduced nanowatt wake-up radio which allows a sensor node to actively listen for packets even when the rest of the node is asleep. CDMA codes and interference rejection reduce the potential for energy-costly false wake-ups. The second prototype is a full transceiver for a body-worn EKG sensor node. Due to size and energy limitations, this transceiver has low instantaneous power and is able to receive 802.15.6 Wireless Body Area Network packets. The third prototype is a long-range transceiver capable of >1km communication range and able to interface with an existing commercial radio. Both