Microelectromechanical accelerometer with resonance-cancelling control circuit including an idle state

• Main Authors: CHU DAHLON D, THELEN, JR. DONALD C, CAMPBELL DAVID V
• Format: Patent
• Language: English
• Published: 16.10.2001
• Edition: 7
• Subjects: INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT; MEASURING; MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION,OR SHOCK; PHYSICS; TESTING

A digital feedback control circuit is disclosed for use in an accelerometer (e.g. a microelectromechanical accelerometer). The digital feedback control circuit, which periodically re-centers a proof mass in response to a sensed acceleration, is based on a sigma-delta (SIGMADELTA) configuration that includes a notch filter (e.g. a digital switched-capacitor filter) for rejecting signals due to mechanical resonances of the proof mass and further includes a comparator (e.g. a three-level comparator). The comparator generates one of three possible feedback states, with two of the feedback states acting to re-center the proof mass when that is needed, and with a third feedback state being an "idle" state which does not act to move the proof mass when no re-centering is needed. Additionally, the digital feedback control system includes an auto-zero trim capability for calibration of the accelerometer for accurate sensing of acceleration. The digital feedback control circuit can be fabricated using complementary metal-oxide semiconductor (CMOS) technology, bi-CMOS technology or bipolar technology and used in single- and dual-proof-mass accelerometers.