Page 129 - DCAP108_DIGITAL_CIRCUITS_AND_LOGIC_DESIGNS
P. 129
Digital Circuits and Logic Design
Notes
alarms, mobile electronics, global positioning systems, elevator controls, patient monitoring
devices and head-mounted displays for gaming.
MEMS Designs, CMOS Fabrication
To take advantage of lower fabrication costs, MEMSIC designs its sensors almost exclusively
with standard CMOS layers: for example, the heater is gate polysilicon and the first layer of
the thermopile is metal and polysilicon.
“We have a tremendous advantage over our competitors,” continues Yongyao. “Our process
is almost independent of the fabrication foundry because our design is 95-99% CMOS. We
can easily change process and foundry to take advantage of better production pricing. Our
competitors, on the other hand, use proprietary MEMS processes, fabricating either by
themselves or through a specialized foundry, and that is always more expensive than working
with a traditional CMOS foundry.”
MEMSIC also enjoys an advantage when changing geometry. Most of its competitors are still
producing at 1-2 micron, and a change to .25 micron in MEMS would result in a completely
different process and a costly conversion. MEMSIC has produced in .6 and .25 micron—with
.18 micron on the roadmap—and its standard CMOS IC process allows it to ramp up volume
and production quickly after a change in geometry.
92,000 Accelerometers in Beijing
The marquee application of MEMSIC’s technology was in the electronic “Waving Torch”
distributed to all attendees of the opening ceremonies for the 2008 Olympics in Beijing.
The torch resembles a 20-30cm wand, with a linear array of LEDs. Shaken from side to side,
the torch tricks the human eye into seeing iconic Olympic images—symbols for major sports,
the Olympic logo, Chinese greetings, and the five Olympic mascots—displayed in mid-air as
the LEDs switch on and off. The core technology in the torch includes a MEMSIC algorithm
and accelerometer (designed with Tanner tools) to detect the user’s back-and-forth hand
movement and to fire each LED as needed for the image.
“We worked on this project for half a year as an Olympic promotional tool,” says Yongyao.
“The user waves the torch through the air, and the LEDs display the pattern according to
the motion. It is a good example of how much information an accelerometer can provide on
position, orientation and speed.”
About MEMSIC
MEMSIC, Inc. designs, manufactures and markets CMOS Micro-Electro-Mechanical Systems
(MEMS) IC products that have on-chip mixed signal processing. MEMSIC is the first and the
only company that integrates a MEMS inertial sensor with mixed signal processing circuitry
onto a single chip using a standard CMOS IC process. This combination of technology has
successfully yielded products at substantially lower cost and higher system performance
and functionality than competitive products in the market for sophisticated accelerometers.
In addition, this technological approach allows the Company to easily integrate additional
functions, or create new sensors, using a standard CMOS IC process to expand into other
MEMS application areas beyond accelerometers.
The Company’s accelerometers, sometimes called inertial sensors, are used to measure tilt
or inclination, shock or vibration, or inertial acceleration. Any application that requires the
control or measurement of motion is a potential application for accelerometers.
Contd....
124 LOVELY PROFESSIONAL UNIVERSITY