MEMS INERTIAL SENSOR WITH FREQUENCY CONTROL AND METHOD
First Claim
1. An inertial sensor, comprising:
- a drive oscillator;
a transducer unit having a first input coupled to the drive oscillator, an output providing a signal responsive to motion of the transducer unit experiencing an angular velocity, a second input, and a third input, wherein the transducer unit includes a sense resonator;
a frequency tuning unit having an output coupled to the second input of the transducer for altering a resonant frequency of the sense resonator of the transducer, and an input;
a capacitance-to-voltage amplifier having an input coupled to the output of the sense resonator, and an output;
a synchronous demodulator having an input coupled to the output of the capacitance-to-voltage amplifier, and an output providing a pair of baseband signals, wherein one of the pair is representative of the angular velocity;
a transducer feedback control system having a pair of inputs for receiving the pair of baseband signals, and an output coupled to the third input of the transducer unit; and
extraction means for performing a Goertzel algorithm on the pair of baseband signals, multiplying results of performing the Goertzel algorithm, and providing a signal on an output responsive to the results, wherein the output of the extraction means is coupled to the input of the frequency tuning unit.
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Accused Products
Abstract
An inertial sensor has a transducer with a sense resonator. The sense resonator is oscillated. A signal responsive to the oscillation is provided. A first baseband signal and a second baseband signal are provided responsive to the signal responsive to the oscillation of the sense resonator. A signal for controlling a resonance frequency of the sense resonator is provided responsive to performing a Goertzel algorithm on the first baseband signal and the second baseband signal. One use of controlling the resonance frequency is to control an offset between the resonance frequency of the sense resonator and the frequency of the oscillation of drive masses in the sense resonator. Using the Goertzel algorithm is particularly efficient in controlling the resonance frequency.
60 Citations
20 Claims
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1. An inertial sensor, comprising:
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a drive oscillator; a transducer unit having a first input coupled to the drive oscillator, an output providing a signal responsive to motion of the transducer unit experiencing an angular velocity, a second input, and a third input, wherein the transducer unit includes a sense resonator; a frequency tuning unit having an output coupled to the second input of the transducer for altering a resonant frequency of the sense resonator of the transducer, and an input; a capacitance-to-voltage amplifier having an input coupled to the output of the sense resonator, and an output; a synchronous demodulator having an input coupled to the output of the capacitance-to-voltage amplifier, and an output providing a pair of baseband signals, wherein one of the pair is representative of the angular velocity; a transducer feedback control system having a pair of inputs for receiving the pair of baseband signals, and an output coupled to the third input of the transducer unit; and extraction means for performing a Goertzel algorithm on the pair of baseband signals, multiplying results of performing the Goertzel algorithm, and providing a signal on an output responsive to the results, wherein the output of the extraction means is coupled to the input of the frequency tuning unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An inertial sensor, comprising:
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a transducer that provides responsive to motion having an angular rate component, wherein the transducer comprises a sense resonator, wherein the sense resonator comprises a drive resonator; a capacitance-to-voltage amplifier, coupled to the transducer, having an output for providing a signal responsive to the motion having an angular rate component; an oscillator, coupled to the transducer, that establishes a frequency of the drive resonator in a first phase; a pilot tone generator for providing a pilot tone at a pilot frequency; feedback means coupled to the pilot tone generator and responsive to the signal provided by the capacitance-to-voltage amplifier for providing a correction signal that includes the pilot frequency to the transducer, wherein the sense resonator responds to the pilot tone with an oscillation in a second phase substantially electrically orthogonal to the first phase; and dynamic frequency control means, responsive to the signal provided by the capacitance-to-voltage amplifier, for providing a signal for use in controlling a resonance frequency of the sense resonator. - View Dependent Claims (12, 13, 14, 15)
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16. A method of operating an inertial sensor having a transducer with a sense resonator, comprising:
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causing an oscillation of the sense resonator; providing a signal responsive to the oscillation of the sense resonator; providing a first baseband signal and a second baseband signal responsive to the signal responsive to the oscillation of the sense resonator; providing a signal for controlling a resonance frequency of the transducer responsive to performing a Goertzel algorithm on the first baseband signal and the second baseband signal. - View Dependent Claims (17, 18, 19, 20)
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Specification