ACCURATE NINETY-DEGREE PHASE SHIFTER
First Claim
1. An apparatus comprising:
- a drive signal circuit for a micro-electromechanical system (MEMS) sensor, the drive signal circuit comprising;
an input configured to receive a voltage signal representative of charge generated by the MEMS sensor;
a phase-shift circuit electrically coupled to the input and configured to phase shift an input signal by substantially ninety degrees;
a comparator circuit with hysteresis, wherein an input of the comparator is electrically coupled to an output of the phase-shift circuit and an output of the comparator circuit is electrically coupled to an output of the drive signal circuit; and
a feedback loop extending from the output of the drive signal circuit to the input of the phase-shift circuit, wherein the feedback loop is configured to generate a self-oscillating signal at an output of the drive signal circuit, andwherein an output signal generated by the drive signal circuit is applied to a drive input of the MEMS sensor.
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Accused Products
Abstract
An apparatus includes a drive signal circuit for MEMS sensor. The drive signal circuit includes an input configured to receive a voltage signal representative of charge generated by the MEMS sensor, a phase-shift circuit electrically coupled to the input and configured to phase shift an input signal by substantially ninety degrees, and a comparator circuit with hysteresis. An input of the comparator is electrically coupled to an output of the phase-shift circuit and an output of the comparator circuit is electrically coupled to an output of the drive signal circuit. A feedback loop extends from the output of the drive signal circuit to the input of the phase-shift circuit and is configured to generate a self-oscillating signal at an output of the drive signal circuit. An output signal generated by the drive signal circuit is applied to a drive input of the MEMS sensor.
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Citations
24 Claims
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1. An apparatus comprising:
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a drive signal circuit for a micro-electromechanical system (MEMS) sensor, the drive signal circuit comprising; an input configured to receive a voltage signal representative of charge generated by the MEMS sensor; a phase-shift circuit electrically coupled to the input and configured to phase shift an input signal by substantially ninety degrees; a comparator circuit with hysteresis, wherein an input of the comparator is electrically coupled to an output of the phase-shift circuit and an output of the comparator circuit is electrically coupled to an output of the drive signal circuit; and a feedback loop extending from the output of the drive signal circuit to the input of the phase-shift circuit, wherein the feedback loop is configured to generate a self-oscillating signal at an output of the drive signal circuit, and wherein an output signal generated by the drive signal circuit is applied to a drive input of the MEMS sensor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of generating a drive signal for a MEMS sensor, the method comprising:
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self-generating an oscillating signal at an output of a drive signal circuit and applying the oscillating signal to a drive input of the MEMS sensor; receiving, at an input of the drive signal circuit, a voltage signal representative of charge generated by the MEMS sensor in response to applying the oscillation signal to the drive input of the MEMS sensor; shifting the phase of the received voltage signal by substantially ninety degrees and using the phase shifted signal to generate the drive signal; and applying the generated drive signal to the drive input of the MEMS sensor. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A method of forming a drive signal circuit for a MEMS sensor, the method comprising:
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electrically coupling an input of the drive signal circuit to an integrator circuit; electrically coupling an output of the integrator circuit to a comparator circuit having hysteresis; and forming a feedback loop in the drive circuit to generate a self-oscillating signal at an output of the drive signal circuit when circuit power is applied to the drive signal circuit, wherein the feedback loop extends from the output of the comparator circuit to an input of an amplifier of the integrator circuit, wherein the integrator circuit shifts the phase angle of an input signal received at the input to the drive signal circuit by substantially ninety degrees, and wherein the input signal is generated in response to applying the self-oscillating signal to a drive input of the MEMS sensor. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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Specification