Semiconductor device and method of direct measurement and acquisition of MEMS employing sigma-delta loop
First Claim
1. A measurement circuit for a microelectromechanical system (MEMS), comprising:
- a sensing node for measuring a state of the MEMS;
an integrator;
a first capacitor including a first terminal of the first capacitor connected to the sensing node and a second terminal of the first capacitor connected to an input of the integrator, wherein the input of the integrator is connected to the sensing node through the first capacitor;
a reference voltage circuit node connected to the second terminal of the first capacitor;
an analog-to-digital converter (ADC) including an input coupled to an output of the integrator and an output providing a digital signal representative of the state of the MEMS;
a digital-to-analog converter (DAC) including an input coupled to the output of the ADC; and
a second capacitor including a first terminal of the second capacitor connected to an output of the DAC and a second terminal of the second capacitor connected to the sensing node, wherein the input of the integrator is connected to the output of the DAC through the first capacitor and second capacitor.
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Abstract
A semiconductor device measures a state of a MEMS as a first voltage variation at a sensing node. The state of the MEMS includes a capacitance. A first capacitor is coupled between the sensing node and an input of an integrator for transferring the first voltage variation to a second node as a first signal. A second voltage variation is routed through a second capacitor to the second node as a second signal. The integrator integrates the first signal and second signal to provide an integrated signal. An ADC has an input coupled to an output of the integrator and converts the integrated signal to a digital signal representative of the capacitance of the MEMS. A DAC has an input coupled to the output of the ADC. A second capacitor is coupled between an output of the DAC and the sensing node.
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Citations
19 Claims
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1. A measurement circuit for a microelectromechanical system (MEMS), comprising:
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a sensing node for measuring a state of the MEMS; an integrator; a first capacitor including a first terminal of the first capacitor connected to the sensing node and a second terminal of the first capacitor connected to an input of the integrator, wherein the input of the integrator is connected to the sensing node through the first capacitor; a reference voltage circuit node connected to the second terminal of the first capacitor; an analog-to-digital converter (ADC) including an input coupled to an output of the integrator and an output providing a digital signal representative of the state of the MEMS; a digital-to-analog converter (DAC) including an input coupled to the output of the ADC; and a second capacitor including a first terminal of the second capacitor connected to an output of the DAC and a second terminal of the second capacitor connected to the sensing node, wherein the input of the integrator is connected to the output of the DAC through the first capacitor and second capacitor. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of measuring a microelectromechanical system (MEMS), comprising:
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sensing a state of the MEMS as a first voltage variation at a sensing node; transferring the first voltage variation through a first capacitor to a second node as a first signal; providing a second voltage variation through a second capacitor to the second node as a second signal; integrating a total charge from the first capacitor and second capacitor at the second node to provide an integrated signal; converting the integrated signal to a digital signal representative of the state of the MEMS; converting the digital signal to an analog signal; and routing the analog signal through a third capacitor to the sensing node. - View Dependent Claims (8, 9, 10, 11)
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12. A semiconductor device for measuring a microelectromechanical system (MEMS), comprising:
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a sensing node for measuring the MEMS; a first integrator; a first capacitor coupled in series between the sensing node and an input of the first integrator; a reference voltage node; a second capacitor coupled in series between the reference voltage node and the input of the first integrator, wherein the sensing node and reference voltage node are coupled to the integrator in parallel through the first capacitor and second capacitor respectively; an analog-to-digital converter (ADC) including an input coupled to an output of the first integrator and an output providing a digital signal representative of a state of the MEMS; and a feedback circuit coupled between the output of the ADC and the sensing node with the feedback circuit including a third capacitor coupled in series between the output of the ADC and the sensing node. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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Specification