Ultra-Low Power Wireless Technologies for Sensor Networks


The new field of wireless sensor networks presents manmy opportunities and just as many challenges. One particularly difficult aspect of wireless sensing is the implementation of the radio link.  To enable energy scavenging, a technique that harvests ambient energy to pwoer the sensor node indefinitely, sub-mW power levels are necessary for the reciever. To allow a small node form-factor, all external surface-mount components must be eliminated.  Traditionial RF transceiver design techniques are not suitable for achieving complete integration since they rely on frequency synthesis, requiring a surface mount quartz crystal and a power hungry on-chip phase locked loop.

This thesis demonstrates that sub-threshold RF CMOS circuit design and high quality RF MEMS passive components are useful tools for reducing the power consumption and increasing the level of integration of GHz-range transceivers.  To demonstrate these concepts, two transceivers using these principles were designed, implemented, and tested. One was a multiple channel 3mW receiver. The other is a 400µW super-regenerative receiver with a 1mm^3 total implementation volume. A 20m indoor wireless link and operation with scavenged energy was demonstrated.  Finally, to further address integration concerns, a CMOS/MEMS reference clock was designed to replace the quartz crystal reference and flip-chip techniques were shown to further reduce the transceiver size.

Publication date: 
May 31, 2005
Publication type: 
Ph.D. Dissertation
Otis, B. (2005). Ultra-Low Power Wireless Technologies for Sensor Networks. United States: University of California, Berkeley.

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