Abstract: A micro speaker assembly including a micro speaker having a top plate, a bottom plate parallel to the top plate, a magnet assembly coupled to one of the top plate or the bottom plate, a compliant member positioned between the magnet assembly and the top plate or the bottom plate, the compliant member operable to be displaced in response to an acoustic input, and a voice coil coupled to the compliant member. The assembly further including an optical sensor coupled to the micro speaker, the optical sensor having a light emitter and a light detector, the light emitter and the light detector being fixedly coupled to the top plate or the bottom plate, and the optical sensor being operable to produce a displacement signal corresponding to a displacement of the compliant member and a temperature signal corresponding to a temperature of the magnet assembly.

Abstract: An excitation signal is produced on a plate of an unknown capacitor and on a plate of a known capacitor. The excitation signal is amplified over time to produce a first output signal, with gain that is proportional to capacitance of the unknown capacitor. The excitation signal is also amplified over time to produce a second output signal, with gain that is proportional to capacitance of the known capacitor. Capacitance of the unknown capacitor is computed using a mathematical function of the first and second output signals and the capacitance of the known capacitor, while being insensitive to amplitude of the excitation signal. Other embodiments are also described and claimed.

Abstract: Circuits, methods, and apparatus for grounding contacts in an audio jack. One example may provide a driver, such as a charge pump, driving a first transistor or switch coupled between a first contact in an audio jack and ground, and a second transistor or switch coupled between a second contact in the audio jack and ground. The first transistor or switch and second transistor or switch may be p-channel transistors or n-channel transistors depletion or enhancement-mode transistors, floating-gate transistors, MEMs, relays, or other switching devices. The first and second transistors or switches may be on and conducting when power is removed from the driver.

Abstract: A charge pump circuit having first and second input nodes to be coupled to a first power source, and top and bottom output nodes and an intermediate node. The charge pump circuit produces i) a voltage at the top output node that is higher than a voltage of the intermediate node, and ii) a voltage at the bottom output node that is lower than the voltage of the intermediate node. A bias voltage source has i) an input that is to be coupled to a second power source and ii) an output that produces an output voltage, which is a predetermined proportion of an input voltage at the input and that follows the input voltage downward and upward as the input voltage sags and recovers, respectively. The output of the bias voltage source is directly connected to the intermediate node of the output stage. Other embodiments are also described.

Abstract: A common plate is formed in a moveable element of a device, the device having an actuator coupled to drive the moveable element. A first plate and the common plate together form a first capacitance, while a second plate and the common plate together form a second capacitance, both of which varies as a function of displacement of the moveable element. A measurement circuit has an input coupled to the first plate, while an excitation voltage source has an output coupled to the second plate. A guard voltage source has an output coupled to a conductive portion of the device. Other embodiments are also described and claimed.

Abstract: An audio jack may include two contacts to electrically connect to a ground contact of an audio plug in order to detect that a metallic audio plug is inserted into the audio jack. A first of these two contacts may be grounded to form a current return path that generates a ground voltage at the ground contact of the audio plug. The second of these two contacts may be repurposed after the detection to sense the ground voltage. The sensed ground voltage may be added to right and left audio signals. The net voltages provided to the audio plug may be right and left audio signals that include the sensed ground voltage minus the actual ground voltage at the ground contact of the audio plug. This may remove the ground voltage from the net audio output signals, which may reduce crosstalk.

Abstract: A charge pump circuit having first and second input nodes to be coupled to a first power source, and top and bottom output nodes and an intermediate node. The charge pump circuit produces i) a voltage at the top output node that is higher than a voltage of the intermediate node, and ii) a voltage at the bottom output node that is lower than the voltage of the intermediate node. A bias voltage source has i) an input that is to be coupled to a second power source and ii) an output that produces an output voltage, which is a predetermined proportion of an input voltage at the input and that follows the input voltage downward and upward as the input voltage sags and recovers, respectively. The output of the bias voltage source is directly connected to the intermediate node of the output stage. Other embodiments are also described.

Abstract: A method for audio signal processing, where an audio amplifier drives a load through a connector, using 1) an input audio signal, and 2) a signal from a return pin of the connector. Output headroom of the audio amplifier is automatically detected, while the amplifier is driving the load. A variable resistor circuit that is coupled to provide variable resistance between the return pin of the connector and a ground plane, is automatically adjusted, in response to the detected output headroom of the amplifier. Other embodiments are also described and claimed.

Abstract: A micro speaker having a capacitive sensor to sense a motion of a speaker diaphragm, is disclosed. More particularly, embodiments of the micro speaker include a conductive surface of a diaphragm facing conductive surfaces of several capacitive plate sections across a gap. The diaphragm may be configured to emit sound forward away from a magnet of the micro speaker, and the capacitive plate sections may be supported on the magnet behind the diaphragm. In an embodiment, the gap provides an available travel for the diaphragm, which may be only a few millimeters. A sensing circuit may sense capacitances of the conductive surfaces to limit displacement of the diaphragm to within the available travel.

Abstract: A common plate is formed in a moveable element of a device, the device having an actuator coupled to drive the moveable element. A first plate and the common plate together form a first capacitance, while a second plate and the common plate together form a second capacitance, both of which varies as a function of displacement of the moveable element. A measurement circuit has an input coupled to the first plate, while an excitation voltage source has an output coupled to the second plate. A guard voltage source has an output coupled to a conductive portion of the device. Other embodiments are also described and claimed.

Abstract: A programmed data processor obtains a number of input voltage measurements for a number of speaker drivers, respectively, and a sensed shared current being a measure of current in a single power supply rail that is feeding power to each of a number of audio amplifiers while the audio amplifiers are driving the speaker drivers in accordance with a number of audio channel test signals, respectively. The programmed data processor computes an estimate of electrical input impedance of each of the speaker drivers using the input voltage measurement for the speaker driver and using the sensed shared current. Other embodiments are also described and claimed.

Abstract: A micro speaker having a capacitive sensor to sense a motion of a speaker diaphragm, is disclosed. More particularly, embodiments of the micro speaker include a conductive surface of a diaphragm facing conductive surfaces of several capacitive plate sections across a gap. The diaphragm may be configured to emit sound forward away from a magnet of the micro speaker, and the capacitive plate sections may be supported on the magnet behind the diaphragm. In an embodiment, the gap provides an available travel for the diaphragm, which may be only a few millimeters. A sensing circuit may sense capacitances of the conductive surfaces to limit displacement of the diaphragm to within the available travel.

Abstract: A programmed data processor receives input voltage measurements for a number of speaker drivers, wherein each of the voltage measurements may be a sensed or estimated sequence of time-domain samples of a respective speaker driver input voltage that is over a different time frame. The processor obtains a sensed shared current, being a measure of current in a single power supply rail that is feeding power to each of a number of audio amplifiers, while the audio amplifiers are driving the speaker drivers in accordance with a number of audio channel signals, respectively. The processor computes an estimate of electrical input impedance for each of the speaker drivers using the sensed shared current and the input voltage measurements. Other embodiments are also described and claimed.

Abstract: A method for audio signal processing, where an audio amplifier drives a load through a connector, using 1) an input audio signal, and 2) a signal from a return pin of the connector. Output headroom of the audio amplifier is automatically detected, while the amplifier is driving the load. A variable resistor circuit that is coupled to provide variable resistance between the return pin of the connector and a ground plane, is automatically adjusted, in response to the detected output headroom of the amplifier. Other embodiments are also described and claimed.

Abstract: An audio jack may include two contacts to electrically connect to a ground contact of an audio plug in order to detect that a metallic audio plug is inserted into the audio jack. A first of these two contacts may be grounded to form a current return path that generates a ground voltage at the ground contact of the audio plug. The second of these two contacts may be repurposed after the detection to sense the ground voltage. The sensed ground voltage may be added to right and left audio signals. The net voltages provided to the audio plug may be right and left audio signals that include the sensed ground voltage minus the actual ground voltage at the ground contact of the audio plug. This may remove the ground voltage from the net audio output signals, which may reduce crosstalk.

Abstract: A programmed data processor receives input voltage measurements for a number of speaker drivers, wherein each of the voltage measurements may be a sensed or estimated sequence of time-domain samples of a respective speaker driver input voltage that is over a different time frame. The processor obtains a sensed shared current, being a measure of current in a single power supply rail that is feeding power to each of a number of audio amplifiers, while the audio amplifiers are driving the speaker drivers in accordance with a number of audio channel signals, respectively. The processor computes an estimate of electrical input impedance for each of the speaker drivers using the sensed shared current and the input voltage measurements. Other embodiments are also described and claimed.

Abstract: A programmed data processor obtains a number of input voltage measurements for a number of speaker drivers, respectively, and a sensed shared current being a measure of current in a single power supply rail that is feeding power to each of a number of audio amplifiers while the audio amplifiers are driving the speaker drivers in accordance with a number of audio channel test signals, respectively. The programmed data processor computes an estimate of electrical input impedance of each of the speaker drivers using the input voltage measurement for the speaker driver and using the sensed shared current. Other embodiments are also described and claimed.

Abstract: Circuits, methods, and apparatus for grounding contacts in an audio jack. One example may provide a driver, such as a charge pump, driving a first transistor or switch coupled between a first contact in an audio jack and ground, and a second transistor or switch coupled between a second contact in the audio jack and ground. The first transistor or switch and second transistor or switch may be p-channel transistors or n-channel transistors depletion or enhancement-mode transistors, floating-gate transistors, MEMs, relays, or other switching devices. The first and second transistors or switches may be on and conducting when power is removed from the driver.

Abstract: Semiconductor devices are described that are configured to have a state of operation defined by a connection between at least one inner bump assembly and a selected outer bump assembly. In an implementation, the semiconductor device, which may be a wafer-level (chip-scale) package semiconductor device, includes an integrated circuit chip, a plurality of outer bump assemblies disposed on the chip, and one or more inner bump assemblies disposed on the chip so that the inner bump assemblies are at least partially surrounded by the outer bump assemblies. At least one of the inner bump assemblies is configured to be connected to a selected outer bump assembly to cause the integrated circuit chip to have a desired state of operation.

Abstract: A rail-to-rail amplifier suitable for use in a line-inversion LCD grayscale reference generator comprises a p-type differential pair and a first switchable current source which supplies tail current to the p-type pair in response to a first control signal, and an n-type pair and a second switchable current source which supplies tail current to the n-type pair in response to a second control signal; when its tail current is present, each pair provides a differential output current which varies with a differential input signal. A control circuit provides the control signals such that the first switchable current source is enabled when a voltage applied to the amplifier's input is closer to the amplifier's negative supply rail, and the second switchable current source is enabled when the applied voltage is closer to the amplifier's positive supply rail, such that only one input pair is active at any given time.