Abstract: Systems and methods for electrical testing of noise in a multi-membrane micro-electro-mechanical systems (MEMS) microphone are disclosed. The MEMS system has a test mode that includes placing the microphones' MEMS biasing networks into a reset mode, adjusting the first bias voltage for the first MEMS sensor such that a polarity matches the polarity of the bias voltage of the second MEMS sensor. The MEMS biasing networks are then placed into a sense mode, and a total noise value is obtained for the MEMS microphone system by measurement of the output of the system's preamplifier.

Abstract: Methods and system are described for cancelling interference in a microphone system. A positive bias voltage is applied to a first microphone diaphragm and a negative bias voltage is applied to a second microphone diaphragm. The diaphragms are configured to exhibit substantially the same mechanical deflection in response to acoustic pressures received by the microphone system. A differential output signal is produced by combining a positively-biased output signal from the first microphone diaphragm and a negatively-biased output signal from the second microphone diaphragm. This combining cancels common-mode interferences that are exhibited in both the positively-biased output signal and the negatively-biased output signal.

Abstract: A self-testing electro-mechanical capacitive sensor system. The system includes an electro-mechanical capacitive sensor and a controller. The controller is configured to receive a signal to activate a test mode, and upon receiving the signal to activate the test mode: (a) apply a bias voltage step to the electro-mechanical capacitive sensor, (b) measure a corresponding deflection of a membrane of the electro-mechanical capacitive sensor for the bias voltage as a function of time, and repeat steps (a) and (b) for a plurality of magnitudes of the bias voltage to determine at least one performance parameter of the electro-mechanical capacitive sensor.

Abstract: Systems and methods of generating independent adjustable bias voltages for a differential microphone. The microphone system includes a positive adjustable charge pump, a positive sense capacitor, a negative adjustable charge pump, a negative sense-capacitor, and a differential amplifier. The positive adjustable charge pump is configured to generate a positive bias voltage. The positive sense-capacitor is configured to generate a positive sense voltage based on acoustic pressure from a first direction and the positive bias voltage. The negative adjustable charge pump is configured to generate a negative bias voltage. The negative sense-capacitor is configured to generate a negative sense voltage based on the acoustic pressure from the first direction and the negative bias voltage. The differential amplifier is configured to receive the positive and negative sense voltages. The differential amplifier is also configured to generate a differential voltage based on the positive and negative sense voltages.

Abstract: Systems and methods of generating independent adjustable bias voltages for a differential microphone. The microphone system includes a positive adjustable charge pump, a positive sense capacitor, a negative adjustable charge pump, a negative sense-capacitor, and a differential amplifier. The positive adjustable charge pump is configured to generate a positive bias voltage. The positive sense-capacitor is configured to generate a positive sense voltage based on acoustic pressure from a first direction and the positive bias voltage. The negative adjustable charge pump is configured to generate a negative bias voltage. The negative sense-capacitor is configured to generate a negative sense voltage based on the acoustic pressure from the first direction and the negative bias voltage. The differential amplifier is configured to receive the positive and negative sense voltages. The differential amplifier is also configured to generate a differential voltage based on the positive and negative sense voltages.

Abstract: Systems and methods for electrical testing of noise in a multi-membrane micro-electro-mechanical systems (MEMS) microphone are disclosed. The MEMS system has a test mode that includes placing the microphones' MEMS biasing networks into a reset mode, adjusting the first bias voltage for the first MEMS sensor such that a polarity matches the polarity of the bias voltage of the second MEMS sensor. The MEMS biasing networks are then placed into a sense mode, and a total noise value is obtained for the MEMS microphone system by measurement of the output of the system's preamplifier.

Abstract: Systems and methods of generating independent adjustable bias voltages for a differential microphone. The microphone system includes a positive adjustable charge pump, a positive sense capacitor, a negative adjustable charge pump, a negative sense-capacitor, and a differential amplifier. The positive adjustable charge pump is configured to generate a positive bias voltage. The positive sense-capacitor is configured to generate a positive sense voltage based on acoustic pressure from a first direction and the positive bias voltage. The negative adjustable charge pump is configured to generate a negative bias voltage. The negative sense-capacitor is configured to generate a negative sense voltage based on the acoustic pressure from the first direction and the negative bias voltage. The differential amplifier is configured to receive the positive and negative sense voltages. The differential amplifier is also configured to generate a differential voltage based on the positive and negative sense voltages.

Abstract: A system and method for controlling and adjusting a low-frequency response of a MEMS microphone. The system comprising the MEMS microphone, a controller, and a memory. The MEMS microphone includes a membrane and a plurality of air vents. The membrane configured such that acoustic pressures acting on the membrane cause movement of the membrane. The plurality of air vents are positioned proximate to the membrane. Each air vent of the plurality of air vents are configured to be selectively positioned in an open position or a closed position. The controller determines an integer number of air vents to be placed in the closed positioned, and generate a signal that causes the integer number of air vents to be placed in the closed position and causes any remaining air vents to be placed in the open position.

Abstract: Methods and system are described for cancelling interference in a microphone system. A positive bias voltage is applied to a first microphone diaphragm and a negative bias voltage is applied to a second microphone diaphragm. The diaphragms are configured to exhibit substantially the same mechanical deflection in response to acoustic pressures received by the microphone system. A differential output signal is produced by combining a positively-biased output signal from the first microphone diaphragm and a negatively-biased output signal from the second microphone diaphragm. This combining cancels common-mode interferences that are exhibited in both the positively-biased output signal and the negatively-biased output signal.

Abstract: Methods and system are described for cancelling interference in a microphone system. A positive bias voltage is applied to a first microphone diaphragm and a negative bias voltage is applied to a second microphone diaphragm. The diaphragms are configured to exhibit substantially the same mechanical deflection in response to acoustic pressures received by the microphone system. A differential output signal is produced by combining a positively-biased output signal from the first microphone diaphragm and a negatively-biased output signal from the second microphone diaphragm. This combining cancels common-mode interferences that are exhibited in both the positively-biased output signal and the negatively-biased output signal.

Abstract: Systems and methods for adjusting a bias voltage and gain of the microphone to account for variations in a thickness of a gap between a movable membrane and a stationary backplate in a MEMS microphone due to the manufacturing process. The microphone is exposed to acoustic pressures of a first magnitude and a sensitivity of the microphone is evaluated according to a predetermined sensitivity protocol. The bias voltage of the microphone is adjusted when the microphone does not meet the sensitivity protocol. The microphone is then exposed to acoustic waves of a second magnitude that is greater than the first magnitude and a stability of the microphone is evaluated according to a predetermined stability protocol. The bias voltage and the gain of the microphone are adjusted when the microphone does not meet the stability protocol.

Abstract: A system and method for controlling and adjusting a low-frequency response of a MEMS microphone. The system comprising the MEMS microphone, a controller, and a memory. The MEMS microphone includes a membrane and a plurality of air vents. The membrane configured such that acoustic pressures acting on the membrane cause movement of the membrane. The plurality of air vents are positioned proximate to the membrane. Each air vent of the plurality of air vents are configured to be selectively positioned in an open position or a closed position. The controller determines an integer number of air vents to be placed in the closed positioned, and generate a signal that causes the integer number of air vents to be placed in the closed position and causes any remaining air vents to be placed in the open position.

Abstract: Methods and system are described for cancelling interference in a microphone system. A positive bias voltage is applied to a first microphone diaphragm and a negative bias voltage is applied to a second microphone diaphragm. The diaphragms are configured to exhibit substantially the same mechanical deflection in response to acoustic pressures received by the microphone system. A differential output signal is produced by combining a positively-biased output signal from the first microphone diaphragm and a negatively-biased output signal from the second microphone diaphragm. This combining cancels common-mode interferences that are exhibited in both the positively-biased output signal and the negatively-biased output signal.

Abstract: A semiconductor microphone including a silicon substrate having a perimeter; an N-well diffused into the substrate at the perimeter; a deformable diaphragm disposed over at least a portion of the silicon substrate and in contact with at least a portion of the perimeter; and a signal channel in electrical communication with the diaphragm. The signal channel includes a microphone output channel and a feedback output channel. The diaphragm produces an electric signal on the signal channel in response to deformation of the diaphragm and a portion of the electric signal is transmitted on the feedback output channel to the N-well.

Abstract: Systems and methods for adjusting a bias voltage and gain of the microphone to account for variations in a thickness of a gap between a movable membrane and a stationary backplate in a MEMS microphone due to the manufacturing process. The microphone is exposed to acoustic pressures of a first magnitude and a sensitivity of the microphone is evaluated according to a predetermined sensitivity protocol. The bias voltage of the microphone is adjusted when the microphone does not meet the sensitivity protocol. The microphone is then exposed to acoustic waves of a second magnitude that is greater than the first magnitude and a stability of the microphone is evaluated according to a predetermined stability protocol. The bias voltage and the gain of the microphone are adjusted when the microphone does not meet the stability protocol.

Abstract: A semiconductor microphone including a silicon substrate having a perimeter; an N-well diffused into the substrate at the perimeter; a deformable diaphragm disposed over at least a portion of the silicon substrate and in contact with at least a portion of the perimeter; and a signal channel in electrical communication with the diaphragm. The signal channel includes a microphone output channel and a feedback output channel. The diaphragm produces an electric signal on the signal channel in response to deformation of the diaphragm and a portion of the electric signal is transmitted on the feedback output channel to the N-well.

Abstract: A method and circuit (40) for tuning a Gm/C filter. A first circuit portion includes a variable current source (52) having a plurality of transistors M15 through M20 coupled to switches SWA through SWMAX. The output capacitor CINT is calibrated iteratively by compensating a calibration capacitor CINTC with the variable current source to tune the Gm/C filter. The transconductance Gm is dependent on a precision external resistor Rext rather than on internal resistors of the Gm/C filter. An algorithm (74) performs the iterative calibrations for the Gm/C filter. The invention is particularly useful for mixed signal or analog circuits.