News Article
Accelerating To Gyro MEMS
Analog Devices (ADI) claims the world's first MEMS-based gyroscope. The
company says that it is the first commercially available device to integrate
both an angular rate sensor and signal processing electronics onto a single
piece of silicon. This integration allows the iMEMS ADXRS gyro to be
smaller, more accurate, more reliable, and more economical than other
angular rate sensors in its class, says ADI.
The gyro is mounted inside a 7x7x3mm ball grid array (BGA) package and
consumes only 5mA of current at 5V. The gyro has a full mechanical and
electronic self-test feature that can operate while the sensor is still
active. The output is stable in the presence of mechanical noise up to 2000g
over a wide frequency range.
The ADI gyroscopes are designed to measure the rate at which objects rotate.
The devices do this by measuring the Coriolis effect that arises in rotating
frames of reference. This effect deflects wind and plughole patterns to the
right (left) in the Northern (Southern) hemisphere. The ADI device has two
vibrating plates oscillating in anti-phase. Any deflection at right angles
to the motion gives a measure of the rotation in the plane of the plates. By
having the two plates, ADI can remove noise from shocks and other
vibrations.
An ADI scientist claims a detectable deflection of 16Fermi (16fm or
0.00016Angstrom). Given that the effective radius of protons and neutrons is
at the Fermi level, this is almost unbelievable. The name "Heisenberg" comes
to mind. A request has been put in to ADI for further clarification of this
figure.
Another incredibly small figure is in the detectable change in capacitance
(12zeptoFarad or 12zF) used to derive the rotation measurement. A "zepto" is
10E-21 - and I had just got used to "atto" (10E-18), used in some recent
short-time measurements. For reference, beyond "nano" (10E-9), we also have
"pico" (10E-12) and "femto" (10E-15).
The information provided by gyros can be used to trigger automobile airbags
during rollover, improve the accuracy and reliability of GPS/navigation
systems and stabilise moving platforms such as automobiles, airplanes,
robots, antennas and industrial equipment.
One company already using the ADI device is Fibersense Technology. Michael S
Perlmutter, executive vice-president at Fibersense, explains: "Analog
Devices' ADXRS gyro has a very low noise output which enables us to use it
in many applications to augment GPS receivers where critical location
information is required during temporary disruptions of GPS signals. In our
product designs, reliability is critical and immunity to shock and vibration
is a must. Competitive solutions were not able to match Analog Devices in
terms of size, performance or reputation for MEMS reliability."
The ADXRS gyro is offered in two versions to accommodate different
requirements for dynamic range. The ADXRS300 provides a dynamic range of
300degrees/second, and the ADXRS150 provides 150degrees/second. Both are
priced at $30 per unit in thousand piece quantities. Samples are currently
available and both products will be in full production by the end of 2002.
Franklin Weigold, vice president and general manager of ADI's Micromachined
Products Division, says: "Using the iMEMS process, we can offer our
customers a roadmap that will provide high quality, high performance gyros
for as little as $10."
The iMEMS (integrated Micro Electro Mechanical System) process is a surface
micromachining technology that ADI has used to make more than 100mn
accelerometers since 1993.
consumes only 5mA of current at 5V. The gyro has a full mechanical and
electronic self-test feature that can operate while the sensor is still
active. The output is stable in the presence of mechanical noise up to 2000g
over a wide frequency range.
The ADI gyroscopes are designed to measure the rate at which objects rotate.
The devices do this by measuring the Coriolis effect that arises in rotating
frames of reference. This effect deflects wind and plughole patterns to the
right (left) in the Northern (Southern) hemisphere. The ADI device has two
vibrating plates oscillating in anti-phase. Any deflection at right angles
to the motion gives a measure of the rotation in the plane of the plates. By
having the two plates, ADI can remove noise from shocks and other
vibrations.
An ADI scientist claims a detectable deflection of 16Fermi (16fm or
0.00016Angstrom). Given that the effective radius of protons and neutrons is
at the Fermi level, this is almost unbelievable. The name "Heisenberg" comes
to mind. A request has been put in to ADI for further clarification of this
figure.
Another incredibly small figure is in the detectable change in capacitance
(12zeptoFarad or 12zF) used to derive the rotation measurement. A "zepto" is
10E-21 - and I had just got used to "atto" (10E-18), used in some recent
short-time measurements. For reference, beyond "nano" (10E-9), we also have
"pico" (10E-12) and "femto" (10E-15).
The information provided by gyros can be used to trigger automobile airbags
during rollover, improve the accuracy and reliability of GPS/navigation
systems and stabilise moving platforms such as automobiles, airplanes,
robots, antennas and industrial equipment.
One company already using the ADI device is Fibersense Technology. Michael S
Perlmutter, executive vice-president at Fibersense, explains: "Analog
Devices' ADXRS gyro has a very low noise output which enables us to use it
in many applications to augment GPS receivers where critical location
information is required during temporary disruptions of GPS signals. In our
product designs, reliability is critical and immunity to shock and vibration
is a must. Competitive solutions were not able to match Analog Devices in
terms of size, performance or reputation for MEMS reliability."
The ADXRS gyro is offered in two versions to accommodate different
requirements for dynamic range. The ADXRS300 provides a dynamic range of
300degrees/second, and the ADXRS150 provides 150degrees/second. Both are
priced at $30 per unit in thousand piece quantities. Samples are currently
available and both products will be in full production by the end of 2002.
Franklin Weigold, vice president and general manager of ADI's Micromachined
Products Division, says: "Using the iMEMS process, we can offer our
customers a roadmap that will provide high quality, high performance gyros
for as little as $10."
The iMEMS (integrated Micro Electro Mechanical System) process is a surface
micromachining technology that ADI has used to make more than 100mn
accelerometers since 1993.