Force feedback loop for pressure sensors
First Claim
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1. A pressure sensor system, comprising:
- a pressure sensor configured to measure a force caused by a pressure and to generate a sensor signal based on the measured pressure force and an electrostatic force; and
a force feedback loop configured to receive the sensor signal and to generate an output signal and a feedback signal based on the sensor signal;
wherein the feedback signal is utilized to generate the electrostatic force on the pressure sensor, wherein the electrostatic force is exerted on the pressure sensor in addition to the pressure force;
wherein the pressure sensor is a capacitive sensor and is configured to generate an overall capacitance associated with the sensor signal, wherein the overall capacitance is caused by an overall force exerted to the pressure sensor by the electrostatic force and the measured pressure, wherein the overall capacitance is equal to or greater than a capacitance caused by a maximum measured pressure applied to the pressure sensor;
wherein the feedback signal or the output signal is converted to a bias voltage to provide a target charge to be compared with a measurement charge.
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Abstract
A pressure sensor system comprises a force feedback loop. The force feedback loop is configured to receive a measured pressure sensor signal and generate a feedback signal based on the measured pressure and an electrostatic force. The electrostatic force is generated based on the feedback signal and combined with the measured force keeping the resultant sensor signal stable.
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Citations
18 Claims
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1. A pressure sensor system, comprising:
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a pressure sensor configured to measure a force caused by a pressure and to generate a sensor signal based on the measured pressure force and an electrostatic force; and a force feedback loop configured to receive the sensor signal and to generate an output signal and a feedback signal based on the sensor signal; wherein the feedback signal is utilized to generate the electrostatic force on the pressure sensor, wherein the electrostatic force is exerted on the pressure sensor in addition to the pressure force; wherein the pressure sensor is a capacitive sensor and is configured to generate an overall capacitance associated with the sensor signal, wherein the overall capacitance is caused by an overall force exerted to the pressure sensor by the electrostatic force and the measured pressure, wherein the overall capacitance is equal to or greater than a capacitance caused by a maximum measured pressure applied to the pressure sensor; wherein the feedback signal or the output signal is converted to a bias voltage to provide a target charge to be compared with a measurement charge. - View Dependent Claims (2, 3, 4)
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5. A signal processing system, comprising:
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an input stage configured to measure a source force and to generate a capacitive signal in response to the measured source force and an electrostatic force; a force feedback loop configured to receive the capacitive signal and to generate an output signal and a feedback driving voltage based on the capacitive signal; and a force function component configured to generate the electrostatic force based on the feedback driving voltage; wherein the electrostatic force is combined with the measured source force to generate an overall force; wherein the force feedback loop comprises an analog controller including a first integrator stage configured to run at a relatively lower clock frequency and a second analog stage having an interpolation character and configured to run at a relatively higher frequency; wherein the first integrator stage introduces a DC pole into an open loop before a signal is quantized, wherein the DC pole turns into a zero for a quantization noise transfer function of a closed control loop. - View Dependent Claims (6, 7)
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8. A signal processing system, comprises:
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an input stage configured to measure a source force and to generate a capacitive signal in response to the measured source force and an electrostatic force; a force feedback loop configured to receive the capacitive signal and to generate an output signal and a feedback driving voltage based on the capacitive signal; a force function component configured to generate the electrostatic force based on the feedback driving voltage; a controller configured to compare a measurement charge and a target charge, and generate a control signal in response to a charge difference; a digital to analog converter (DAC) configured to convert the control signal to a feedback voltage; an amplifier configured to amplify the feedback voltage to form the feedback driving voltage; and a switched capacitor circuit configured to generate a comparison result of the measurement charge and the target charge; wherein the switched capacitor circuit comprises a programmable array of capacitors connected in parallel to a capacitor of a sensor bridge. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A method of operating a pressure sensor system comprises:
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using a pressure sensor to generate a sensor signal based on the measured pressure and an electrostatic force applied to the pressure sensor; comparing the sensor signal with a target charge to generate an output signal and a feedback signal via a force feedback loop; converting the feedback signal to a voltage signal and amplifying the voltage signal to a feedback driving voltage greater than the voltage signal; generating a new electrostatic force using the feedback driving voltage as a first bias voltage; and applying the new electrostatic force to the pressure sensor in addition to a force caused by the measured pressure to generate a new sensor signal; wherein the target charge is generate using the voltage signal as a second bias voltage, the second bias voltage being smaller than the first bias voltage. - View Dependent Claims (17, 18)
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Specification