Abstract: A microphone assembly includes a housing including a sound port and an external-device interface having a plurality of electrical contacts. An acoustic transducer, such as a MEMS microphone, is disposed in the housing and is in acoustic communication with the sound port. An electrical circuit is disposed in the housing that is electrically coupled to the acoustic transducer and to electrical contacts on the external-device interface. A magnetic transducer including an electrical coil disposed about a core, such as a telecoil or charging coil configuration, is fastened to the housing. The electrical coil having leads, at least one of the leads electrically terminated at a coil contact of the housing.

Abstract: A microphone assembly includes a housing including a sound port and an external-device interface having a plurality of electrical contacts. An acoustic transducer, such as a MEMS microphone, is disposed in the housing and is in acoustic communication with the sound port. An electrical circuit is disposed in the housing that is electrically coupled to the acoustic transducer and to electrical contacts on the external-device interface. A magnetic transducer including an electrical coil disposed about a core, such as a telecoil or charging coil configuration, is fastened to the housing. The electrical coil having leads, at least one of the leads electrically terminated at a coil contact of the housing.

Abstract: A sensor assembly including a capacitive sensor, like a microelectromechanical (MEMS) microphone, and an electrical circuit therefor are disclosed. The electrical circuit includes a first transistor having an input gate connectable to the capacitive sensor, a second transistor having an input gate coupled to an output of the first transistor, a feedforward circuit interconnecting a back-gate of the second transistor and the output of the first transistor, and a filter circuit interconnecting the output of the first transistor and the input gate of the second transistor.

Abstract: Sound-producing acoustic receivers and hearing devices implementing such receivers are disclosed. The acoustic receiver includes a receiver housing, an output port, a receiver motor assembly, and a transducer. The receiver housing includes a diaphragm that separates the receiver housing into a back volume and a front volume. The output port is located on the receiver housing and acoustically coupled to the front volume of the receiver housing. The receiver motor assembly is disposed in the back volume and is mechanically coupled to the diaphragm. The transducer is fastened to the receiver housing.

Abstract: A micro-electromechanical system (MEMS) transducer assembly includes a transducer including a condenser microphone, an integrated circuit electrically connected to the transducer to receive an output voltage from the transducer, wherein the integrated circuit comprises a test signal generator configured to induce a test acoustic response in the transducer, and an evaluation circuit configured to compare the test acoustic response to a baseline acoustic response to identify a fault in the transducer.

Abstract: A sensor assembly including a capacitive sensor, like a microelectromechanical (MEMS) microphone, and an electrical circuit therefor are disclosed. The electrical circuit includes a first transistor having an input gate connectable to the capacitive sensor, a second transistor having an input gate coupled to an output of the first transistor, a feedforward circuit interconnecting a back-gate of the second transistor and the output of the first transistor, and a filter circuit interconnecting the output of the first transistor and the input gate of the second transistor.

Abstract: Sound-producing acoustic receivers and hearing devices implementing such receivers are disclosed. The acoustic receiver includes a receiver housing, an output port, a receiver motor assembly, and a transducer. The receiver housing includes a diaphragm that separates the receiver housing into a back volume and a front volume. The output port is located on the receiver housing and acoustically coupled to the front volume of the receiver housing. The receiver motor assembly is disposed in the back volume and is mechanically coupled to the diaphragm. The transducer is fastened to the receiver housing.

Abstract: A microphone assembly includes a housing including a sound port and an external-device interface having a plurality of electrical contacts. An acoustic transducer, such as a MEMS microphone, is disposed in the housing and is in acoustic communication with the sound port. An electrical circuit is disposed in the housing that is electrically coupled to the acoustic transducer and to electrical contacts on the external-device interface. A magnetic transducer including an electrical coil disposed about a core, such as a telecoil or charging coil configuration, is fastened to the housing. The electrical coil having leads, at least one of the leads electrically terminated at a coil contact of the housing.

Abstract: A micro-electromechanical system (MEMS) transducer assembly includes a transducer including a condenser microphone, an integrated circuit electrically connected to the transducer to receive an output voltage from the transducer, wherein the integrated circuit comprises a test signal generator configured to induce a test acoustic response in the transducer, and an evaluation circuit configured to compare the test acoustic response to a baseline acoustic response to identify a fault in the transducer.

Abstract: A microphone circuit having an amplifier with an input operably coupled to a microphone motor also includes a low pass filter operably coupled to the output of the amplifier and a positive feedback network that operably couples to an output of the low-pass filter and to the amplifier input. For many useful application settings the aforementioned amplifier has unity gain while the positive feedback network has a fractional gain less than unity.

Abstract: A microphone circuit having an amplifier with an input operably coupled to a microphone motor also includes a low pass filter operably coupled to the output of the amplifier and a positive feedback network that operably couples to an output of the low-pass filter and to the amplifier input. For many useful application settings the aforementioned amplifier has unity gain while the positive feedback network has a fractional gain less than unity.

Abstract: A MOSFET active-disable switch is configured to clip an incoming signal in opposing directions when in an off state. By one approach the clipping is symmetrical and accordingly the switch clips both positive and negative peaks of the incoming signal. In many application settings it is useful for the clipping to serve to decrease a predetermined kind of resultant distortion such as even order distortion. In the on state this MOSFET active-disable switch is configured to not clip the incoming signal in opposing directions.

Abstract: A direct current (DC) bias maintenance circuit operably couples to the input of a primary amplifier. The DC bias maintenance circuit employs feedback to maintain the desired DC bias but lacks any coupling to the output of the primary amplifier. By one approach the DC bias maintenance circuit includes a secondary amplifier that replicates at least some near real-time performance characteristics of the primary amplifier. For example, the secondary amplifier can replicate at least certain DC properties of the primary amplifier such that DC-based changes appearing at the output of the primary amplifier are mirrored at an output of the secondary amplifier notwithstanding a lack of any coupling between the output of the primary amplifier and the DC bias maintenance circuit.

Abstract: A direct current (DC) bias maintenance circuit operably couples to the input of a primary amplifier. The DC bias maintenance circuit employs feedback to maintain the desired DC bias but lacks any coupling to the output of the primary amplifier. By one approach the DC bias maintenance circuit includes a secondary amplifier that replicates at least some near real-time performance characteristics of the primary amplifier. For example, the secondary amplifier can replicate at least certain DC properties of the primary amplifier such that DC-based changes appearing at the output of the primary amplifier are mirrored at an output of the secondary amplifier notwithstanding a lack of any coupling between the output of the primary amplifier and the DC bias maintenance circuit.

Abstract: A MOSFET active-disable switch is configured to clip an incoming signal in opposing directions when in an off state. By one approach the clipping is symmetrical and accordingly the switch clips both positive and negative peaks of the incoming signal. In many application settings it is useful for the clipping to serve to decrease a predetermined kind of resultant distortion such as even order distortion. In the on state this MOSFET active-disable switch is configured to not clip the incoming signal in opposing directions.

Abstract: These teachings provide for detecting an offset voltage corresponding to a circuit element having an input and an output. (The approaches taught herein will accommodate detecting that offset voltage at either the input and/or the output as desired.) Upon detecting the offset voltage a switch that connects the input of the circuit element to ground automatically closes to thereby ground the input. That switch remains open in the absence of detecting an offset voltage.

Abstract: A single-stage buffer apparatus includes a first transistor, a second transistor, and a high pass filter network. The first transistor is configured to receive an input signal from a microphone. The second transistor is configured to operate as a cascode transistor. The high pass filter network is coupled to the first transistor and the second transistor. The second transistor electrically decouples the first transistor from an output of the single-stage buffer apparatus. A gate terminal of the second transistor is driven by the high-pass filter network, and the high-pass filter network is driven by the first transistor.

Abstract: A microphone assembly includes a housing having an interior with a front volume and a back volume. The housing has an acoustic input port coupling the front volume to an exterior of the housing. An acoustic sensor is disposed at least partially within the interior of the housing. At least a portion of the acoustic sensor is disposed at an interface between the front volume and the back volume. The acoustic sensor has an electrical signal output. A circuit board is disposed at least partially within the back volume of the housing and has a conductive member and an electrical contact. The circuit board also has a first portion carrying a first portion of the conductive member, and a second portion of the conductive member extending from the first portion of the circuit board toward the acoustic sensor. The second portion of the conductive member is electrically connected to the electrical signal output of the acoustic sensor.

Abstract: A buffer is coupled to an acoustic motor. The buffer has an input and an output. The input has an input voltage and the output has an output voltage. The buffer is coupled to a load. The buffer includes an input transistor and push-pull transistor circuitry. The input transistor has a gate, a source, and a drain, a gate-to-source capacitance, and an area. The push-pull transistor circuitry is coupled to the input transistor. Under a first set of operating conditions, the gate to source voltage of the input transistor remains constant and the output voltage is a buffered copy of the input voltage. Under a second set of operating conditions, the push-pull transistor circuitry selectively sinks or sources additional current to the load so that linearity of buffer operation is provided. A gate-to-drain capacitance of the input transistor is buffered allowing the area of the input transistor to be increased without reducing the gain of the motor.

Abstract: A dB-linear voltage-to-current (V/I) converter is amenable to implementation in CMOS technology. In a representative embodiment, the dB-linear V/I converter has a voltage scaler, a current multiplier, and an exponential current converter serially connected to one another. The voltage scaler supplies an input current to the current multiplier based on an input voltage. The current multiplier multiplies the input current and a current proportional to absolute temperature and supplies the resulting current to the exponential current converter. The exponential current converter has a differential MOSFET pair operating in a sub-threshold mode and generating an output current that is proportional to a temperature-independent, exponential function of the input voltage.