Sensor having an off-frequency drive scheme and a sense bias generator utilizing tuned circuits
First Claim
1. A sensor system comprising:
- an input transducer receiving a drive signal and converting said drive signal into a force signal having a non-linear relationship with respect to said drive signal;
a sensor responsive to said force signal and an external stimulus for providing a first sensor output signal having a predetermined frequency and being indicative of said force signal and a second sensor output signal having said predetermined frequency and being indicative of said external stimulus;
a frequency translation circuit responsive to said first sensor output signal for suppressing a component of said first sensor output signal at said predetermined frequency to provide a frequency translated signal capable of producing a force at said predetermined frequency; and
a tuned circuit responsive to said frequency translated signal for generating said drive signal, wherein said tuned circuit comprises an inductor and a capacitor for amplifying said frequency translated signal, so as to increase the amplitude of said drive signal.
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Accused Products
Abstract
Electronics for use in Coriolis and other sensors for reducing errors in the sensor output signal. The electronics includes an off-frequency drive scheme for reducing in-band drive signal coupling to the output signal and techniques for reducing errors in the sensor output signal due to quadrature and phase shift. The off-frequency drive scheme includes a frequency translation circuit in the excitation feedback loop of a sensor system to suppress components of the sensor drive signal at a predetermined frequency so that coupling of the drive signal to the sensor output signal can be readily removed by conventional filtering techniques. The sensor system includes a nonlinear input transducer for converting the drive signal to a force signal such that the force signal has a component at the predetermined frequency while the drive signal does not. A tuned circuit amplifies and filters the frequency shifted output signal of the translation circuit to provide the drive signal. Also provided is a sense bias generator including a tuned circuit for amplifying the available bias supply voltage to enhance sensitivity.
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Citations
12 Claims
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1. A sensor system comprising:
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an input transducer receiving a drive signal and converting said drive signal into a force signal having a non-linear relationship with respect to said drive signal; a sensor responsive to said force signal and an external stimulus for providing a first sensor output signal having a predetermined frequency and being indicative of said force signal and a second sensor output signal having said predetermined frequency and being indicative of said external stimulus; a frequency translation circuit responsive to said first sensor output signal for suppressing a component of said first sensor output signal at said predetermined frequency to provide a frequency translated signal capable of producing a force at said predetermined frequency; and a tuned circuit responsive to said frequency translated signal for generating said drive signal, wherein said tuned circuit comprises an inductor and a capacitor for amplifying said frequency translated signal, so as to increase the amplitude of said drive signal. - View Dependent Claims (2, 3, 4, 5)
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6. Apparatus comprising:
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a sensor having a resonant frequency; an electrostatic element responsive to a drive signal having a second frequency for generating a force signal having a component at said resonant frequency to excite said sensor, wherein said second frequency is greater than said resonant frequency; and a tuned circuit comprising at least one capacitor and at least one inductor for amplifying said drive signal provided to said element. - View Dependent Claims (7, 8)
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9. A method for sensing a stimulus comprising the steps of:
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generating a force signal having a first frequency by applying a drive signal having a second frequency greater than said first frequency to an electrostatic element; electrostatically actuating a sensor subjected to said stimulus and having a resonant frequency substantially equal to said first frequency with said force signal; detecting a response of said sensor to said stimulus; and amplifying said drive signal with a tuned circuit comprising at least one capacitor and at least one inductor. - View Dependent Claims (10)
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11. Apparatus comprising:
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an electrostatic element having an admittance; and a tuned circuit having an admittance and comprising at least one capacitor and at least one inductor for amplifying a signal provided to said element, wherein said admittance of said electrostatic element is substantially negligible with respect to said admittance of said tuned circuit.
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12. A sensor system comprising:
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an actuator having an admittance and receiving a drive signal; a sensor responsive to said actuator and to a stimulus for producing an output signal; an electrode biased by a sense bias voltage for sensing said output signal; and a tuned circuit for amplifying at least a selected one of said drive signal and said sense bias voltage, said tuned circuit having an admittance, wherein said admittance of said actuator is substantially negligible with respect to said admittance of said tuned circuit.
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Specification