Sensitivity adjustment apparatus and method for MEMS devices
First Claim
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1. A microelectromechanical (MEMS) microphone comprising:
- a MEMS motor, the MEMS motor including at least a diaphragm and a charge plate, the MEMS motor configured to receive sound energy and transform the sound energy into an electrical signal;
a gain adjustment apparatus, disposed on an integrated circuit and coupled to the MEMS motor, the gain adjustment apparatus comprising;
an input configured to receive the electrical signal from the MEMS motor;
an output;
an amplifier configured to provide an output voltage at the output based upon a gain provided by the amplifier and the electrical signal; and
a plurality of switchable capacitors, each of the plurality of switchable capacitors configured to be selectively connected to the input;
wherein selective connection of the plurality of switchable capacitors to the input causes a sensitivity of the MEMS microphone to be within a predetermined specific target sensitivity range for the MEMS microphone; and
wherein the plurality of switchable capacitors attenuate the output based at least in part upon a capacitance of the MEMS motor, a capacitance of the plurality of switchable capacitors that are connected to the input, and a capacitance of the integrated circuit.
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Abstract
A microelectromechanical (MEMS) microphone includes a MEMS motor and a gain adjustment apparatus. The MEMS motor includes at least a diaphragm and a charge plate and is configured to receive sound energy and transform the sound energy into an electrical signal. The gain adjustment apparatus has an input and an output and is coupled to the MEMS motor. The gain adjustment apparatus is configured to receive the electrical signal from the MEMS motor at the input and adjust the gain of the electrical signal as measured from the output of the gain adjustment apparatus. The amount of gain is selected so as to obtain a favorable sensitivity for the microphone.
58 Citations
20 Claims
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1. A microelectromechanical (MEMS) microphone comprising:
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a MEMS motor, the MEMS motor including at least a diaphragm and a charge plate, the MEMS motor configured to receive sound energy and transform the sound energy into an electrical signal; a gain adjustment apparatus, disposed on an integrated circuit and coupled to the MEMS motor, the gain adjustment apparatus comprising; an input configured to receive the electrical signal from the MEMS motor; an output; an amplifier configured to provide an output voltage at the output based upon a gain provided by the amplifier and the electrical signal; and a plurality of switchable capacitors, each of the plurality of switchable capacitors configured to be selectively connected to the input; wherein selective connection of the plurality of switchable capacitors to the input causes a sensitivity of the MEMS microphone to be within a predetermined specific target sensitivity range for the MEMS microphone; and
wherein the plurality of switchable capacitors attenuate the output based at least in part upon a capacitance of the MEMS motor, a capacitance of the plurality of switchable capacitors that are connected to the input, and a capacitance of the integrated circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of adjusting a microelectromechanical (MEMS) microphone, the method comprising:
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setting a specific target sensitivity value for the MEMS microphone; determining an initial sensitivity value of the MEMS microphone at a predetermined frequency during operation of the MEMS microphone, the MEMS microphone including a MEMS motor that transmits a signal to an amplifier; determining that the initial sensitivity value is outside a predetermined range of the specific target sensitivity value; and adjusting an amount of attenuation of the MEMS microphone by selectively actuating one or more switchable capacitors, wherein the one or more switchable capacitors achieve the specific target sensitivity value based at least in part upon the initial sensitivity value of the MEMS microphone, a capacitance of the MEMS motor, capacitance of the actuated one or more capacitors and a capacitance of the integrated circuit. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification