EECS500 Fall 2011 Department Seminar

Wan-Thai Hsu, Ph.D.
Silicon MEMS Oscillators – from Research to Products
Discera Inc.
White Bldg., Room 411
11:30am - 12:30pm
September 22, 2011


All electronic systems need a frequency reference source for synchronization between functional blocks, or communication with other systems.  This reference frequency acts like the heart beat in the human body – one could not live without it and could not live healthily without its stability.  Over the past few decades, quartz crystals, a type of mechanical vibrating device with extremely stable natural resonance frequency compared to integrated circuit-based resonators such as LC tanks, have provided such function for electronic systems.  However, as integrated circuits follow Moore’s Law – the numbers of transistors doubles every two years, quartz crystals remain unchanged. 
With the progress of micro-electro-mechanical system (MEMS) technologies in the past two decades, micro-scale mechanical resonators can now be fabricated on silicon wafers.  These tiny silicon structures showed similar resonant characteristics as quartz crystals.  With interface and conditioning circuitry, silicon MEMS resonators are able to sustain a stable oscillation across environmental conditions like quartz crystal resonators.  Now, these MEMS-based oscillators have been used in various applications such as consumer electronics, automotive dashboards, and military telemetry.  Meanwhile, they are smaller, cheaper, lower power, and easier for system integration. 
This seminar first reviews the development history of MEMS resonators and oscillators.  The evolution of MEMS resonator designs as well as transducer designs will be discussed, and the interface circuitry that is necessary to deal with special characteristics of MEMS resonators will be presented.  Often taken for granted in research environments, MEMS fabrication processes and wafer level packaging technologies are the two key success factors for any MEMS-based products.  We will review the progress of the MEMS manufacturing environment from research-oriented facilities to mainstream foundries worldwide, and discuss the trend of MEMS foundry business. 
As a result, of all of these advancements, silicon MEMS oscillators have been replacing quartz crystal oscillators in many electronic systems.  In the second part of the seminar, we will discuss how a technology company grew from a research-oriented University spin-off to world-recognized semiconductor company chasing for $4 billion dollar annual market.  The sales for MEMS oscillators have been growing exponentially over the last 3 years, and our work has changed the whole oscillator industry from an old-fashion mechanical industry to a miniaturization, low cost, and integration semiconductor industry


Dr. Wan-Thai Hsu received B.S. and M.S. degrees from National Tsing-Hua University, Taiwan and Ph.D. degree from University of Michigan, all in Electrical Engineering.  He is one of the pioneer researchers and inventors in the area of MEMS resonators and oscillators.  Part of his doctoral work led to the birth of Discera Inc. in 2001.  Currently he is Chief Technology Officer at Discera.  Since 2001, he has successfully led Discera making silicon MEMS oscillators from research to commercial products.  Silicon MEMS oscillator is now an industry with more than 10 players worldwide, targeting more than $4B annual markets.  He published more than 30 technical papers and is a frequent invited speaker in international conferences.  He holds 8 U.S. patents and has 4 patents pending. 

Dr. Hsu was awarded “Innovation of the Year” in 2007 by EE Times Annual Creativity in Electronics award.  Later that year, Discera’s silicon MEMS technology was honored in Wall Street Journal Technical Innovation Award.  Other than his Ph.D., he also received Executive MBA degree from Ross Business School, University of Michigan in 2010.