Drive mode and sense mode resonance frequency matching
First Claim
1. A micro electro mechanical system (MEMS) comprising:
- a proof mass configured to move responsive to stimuli;
sense electrodes configured to generate a signal responsive to the proof mass moving;
sense circuitry coupled to the sense electrodes, wherein the sense circuitry is configured to receive the generated signal and further configured to process the generated signal; and
a frequency matching circuitry configured to apply a direct current (DC) voltage to the sense electrodes, wherein the DC voltage is configured to change a stiffness of a spring of the proof mass and wherein the change in the stiffness of the spring matches a resonance frequency between a sense mode and a drive mode, wherein the frequency matching circuitry comprises;
a diode;
a capacitor coupled to the diode; and
an NMOS switch,wherein the diode is configured to charge the capacitor when the NMOS switch is open, and wherein the NMOS switch is configured to electrically connect the capacitor to the sense electrodes and to the sense circuitry when the NMOS switch is closed, wherein the DC voltage is a voltage from the capacitor being applied to the sense electrodes when the NMOS switch closes, and wherein the diode is electrically disconnected from the capacitor when the NMOS switch is closed, and wherein the NMOS switch is protected against high voltage stress by opening the NMOS switch when the capacitor is being charged by the diode and by closing the NMOS switch when the capacitor is not being charged by the diode.
1 Assignment
0 Petitions
Accused Products
Abstract
In some embodiments, a micro electro mechanical system (MEMS) includes a proof mass, sense electrodes, sense circuitry, and a frequency matching circuitry. The proof mass is configured to move responsive to stimuli. The sense electrodes are configured to generate a signal responsive to the proof mass moving. The sense circuitry is coupled to the sense electrodes. The sense circuitry is configured to receive the generated signal and further configured to process the generated signal. The frequency matching circuitry is configured to apply a DC voltage to the sense electrodes. The DC voltage is configured to change a stiffness of a spring of the proof mass. According to some embodiments, the change in the stiffness of the spring matches a resonance frequency between a sense mode and a drive mode. According to some embodiments, the sense electrodes are a comb structure.
3 Citations
16 Claims
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1. A micro electro mechanical system (MEMS) comprising:
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a proof mass configured to move responsive to stimuli; sense electrodes configured to generate a signal responsive to the proof mass moving; sense circuitry coupled to the sense electrodes, wherein the sense circuitry is configured to receive the generated signal and further configured to process the generated signal; and a frequency matching circuitry configured to apply a direct current (DC) voltage to the sense electrodes, wherein the DC voltage is configured to change a stiffness of a spring of the proof mass and wherein the change in the stiffness of the spring matches a resonance frequency between a sense mode and a drive mode, wherein the frequency matching circuitry comprises; a diode; a capacitor coupled to the diode; and an NMOS switch, wherein the diode is configured to charge the capacitor when the NMOS switch is open, and wherein the NMOS switch is configured to electrically connect the capacitor to the sense electrodes and to the sense circuitry when the NMOS switch is closed, wherein the DC voltage is a voltage from the capacitor being applied to the sense electrodes when the NMOS switch closes, and wherein the diode is electrically disconnected from the capacitor when the NMOS switch is closed, and wherein the NMOS switch is protected against high voltage stress by opening the NMOS switch when the capacitor is being charged by the diode and by closing the NMOS switch when the capacitor is not being charged by the diode. - View Dependent Claims (2, 3, 4, 5)
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6. A micro electro mechanical system (MEMS) comprising:
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a proof mass configured to move responsive to stimuli; sense electrodes configured to generate a signal responsive to the proof mass moving; and a frequency modifying circuitry configured to apply a direct current (DC) voltage to the sense electrodes, wherein the DC voltage is configured to change a stiffness of a spring of the proof mass, and wherein the change in the stiffness of the spring matches a resonance frequency in a sense mode to a resonance frequency in a drive mode, wherein the frequency modifying circuitry comprises; a diode; a capacitor coupled to the diode; and an NMOS switch, wherein the diode is configured to charge the capacitor when the NMOS switch is open, and wherein the NMOS switch is configured to electrically connect the capacitor to the sense electrodes when the NMOS switch is closed, wherein the DC voltage is a voltage from the capacitor being applied to the sense electrodes when the NMOS switch closes, and wherein the diode is electrically disconnected from the capacitor when the NMOS switch is closed, and wherein the NMOS switch is protected against high voltage stress by opening the NMOS switch when the capacitor is being charged by the diode and by closing the NMOS switch when the capacitor is not being charged by the diode. - View Dependent Claims (7, 8, 9)
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10. A micro electro mechanical system (MEMS) comprising:
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a proof mass configured to move responsive to stimuli; sense electrodes configured to generate a signal responsive to the proof mass moving; sense circuitry coupled to the sense electrodes, wherein the sense circuitry is configured to receive the generated signal and further configured to process the generated signal; and a frequency matching circuitry configured to apply a direct current (DC) voltage to the sense electrodes, wherein the DC voltage is configured to change a stiffness of a spring of the proof mass and wherein the change in the stiffness of the spring matches a resonance frequency between a sense mode and a drive mode, wherein the frequency matching circuitry comprises; a PMOS switch; a capacitor coupled to the PMOS switch; and a NMOS switch, wherein the capacitor is configured to charge when the PMOS switch closes and when the NMOS switch opens, and wherein the capacitor is electrically connected to the sense electrodes when the NMOS switch closes and when the PMOS switch opens and wherein the DC voltage is applied to the sense electrodes when the capacitor is electrically connected to the sense electrodes, and wherein the NMOS switch is protected against high voltage stress by opening the NMOS switch when the capacitor is being charged and by closing the NMOS switch when the capacitor is not being charged. - View Dependent Claims (11, 12, 13, 15, 16)
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14. A micro electro mechanical system (MEMS) comprising:
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a proof mass configured to move responsive to stimuli; sense electrodes configured to generate a signal responsive to the proof mass moving; and a frequency modifying circuitry configured to apply a direct current (DC) voltage to the sense electrodes, wherein the DC voltage is configured to change a stiffness of a spring of the proof mass, and wherein the change in the stiffness of the spring matches a resonance frequency in a sense mode to a resonance frequency in a drive mode, wherein the frequency modifying circuitry comprises; a PMOS switch; a capacitor coupled to the PMOS switch; and a NMOS switch, wherein the capacitor is configured to charge when the PMOS switch closes and when the NMOS switch opens, and wherein the capacitor is electrically connected to the sense electrodes when the NMOS switch closes and when the PMOS switch opens and wherein the DC voltage is applied to the sense electrodes when the capacitor is electrically connected to the sense electrodes, and wherein the NMOS switch is protected against high voltage stress by opening the NMOS switch when the capacitor is being charged and by closing the NMOS switch when the capacitor is not being charged.
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Specification