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A capacitive sensing integrated circuit for detection of micromotor critical angles
Arvind Purushotham
Published in Institute of Electrical and Electronics Engineers Inc.
1997
Volume: 32
   
Issue: 1
Pages: 23 - 30
Abstract
The theory, design, and measured performance of an integrated circuit which enables closed-loop control of electrostatic micromotors is presented. The micromotor control integrated circuit (MCIC) consists of low-noise sense electronics designed to detect critical rotor angles to a resolution of 0.5° (0.05 fF) at a 1-MHz sampling rate, and control logic which cycles the micromotor drive state during continuous rotation to maintain maximum torque, independent of loading. Noise due to MOSFET switches and amplifiers in the analog section is modeled and shown to be 32 μV referred to the system input, i.e., about half the desired switching resolution. The MCIC was fabricated using a 2-μm, n-well CMOS process and functions as expected. The noise probability density function was measured using MCIC's digital output for different values of input-to-ground capacitance in order to verify the noise model. Good agreement with theory was observed, although the comparator exhibited some offset and hysteresis.
About the journal
JournalData powered by TypesetIEEE Journal of Solid-State Circuits
PublisherData powered by TypesetInstitute of Electrical and Electronics Engineers Inc.
ISSN00189200
Open AccessNo
Concepts (16)
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    Capacitance measurement
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    Closed loop control systems
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    Cmos integrated circuits
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    Electric motors
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    Mathematical models
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    Mosfet devices
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    Position measurement
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    Probability density function
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    Rotors (windings)
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    Spurious signal noise
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    Torque control
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    CAPACITIVE SENSING INTEGRATED CIRCUIT
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    Control logic
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    ELECTROSTATIC MICROMOTORS
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    MICROMOTOR CONTROL INTEGRATED CIRCUIT (MCIC)
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    SILICON SENSORS