EECS500 Spring 2017 Department Colloquium

Ruonan Liu
All-Mechanical Receivers
University of California, Berkeley
White 411
11:30 AM - 12:30 PM
February 2, 2017

The widespread expectation that autonomous sensor networks will fuel massively accessible information technology, such as the Internet of Things (IoT), comes with the daunting realization that huge numbers of sensor nodes will be required, perhaps approaching one trillion.  Needless to say, besides cost, energy will likely pose a major constraint in such a vision.  High quality factor MEMS resonators are perfect candidates for low power electronics.  Especially resoswitches, short for resonant switches, have demonstrated their capability as all−mechanical receiver front−ends that detect and demodulate signals as low as −60dBm while consuming zero quiescent power!  The key to attaining high quality signal reception and demodulation with zero quiescent power consumption derives from the use of heavily nonlinear amplification, provided by mechanical impact switching of the resoswitch.  This approach would be inconceivable in a conventional receiver due to performance degradation caused by nonlinearity, but becomes plausible here by virtue of the RF channel selection provided by the resonant behavior of the mechanical circuit.  Similar technology has also fueled the development of a real time clock (RTC) that can potentially operate on 5pW of power, 200,000 times lower than a typical commercially available RTC.


Ruonan Liu received her B.S. degree from the Ohio State University, in Electrical Engineering (2011).  Currently, she is a PhD student in EECS department at UC Berkeley, working with Prof. Clark Nguyen.  Ruonan’s research interest mainly focuses on MEMS resonators, specifically micromechanical resonant switches, and the applications of this novel type of MEMS switches such as DC-DC power converters and low power wireless communication networks.  Ruonan is the recipient of the Best Paper Award at the 70th IEEE International Frequency Control Symposium, and the Best Paper Award Finalist at the 18th International Conference on Solid−State Sensors, Actuators and Microsystems (Transducers 2015).  Her paper also won the Best Paper Award at Transducers 2013.