Apple Inc.

Analog Devices,inc.

Maxim Integrated Products, Inc.

Roderick Brian Hogan

Nathan Alan Johanningsmeier

Scott P Porter

Christopher R Wilk

Todd K Moyer

Michael B Nussbaum

Ruchir M Dave

Anand K Chamakura

David C Breece, Iii

Girault W Jones

Hongdan Tao

Kavitha Srinivasan

Joseph C Curcio

Kymberly Tennille Christman

James B Reedy

Evan D Ragsdale

Andrew P Bright

Alexander V Salvatti

Thomas M Jensen

Anthony P Grazian

Cara S Yang

Suzanne C Brown

Casey L Hardy

Troy A Murphy

Yang Boon Quek

Joseph J Curcio

A group of transistors is configured to drive a bus at time slots, to express data on the bus. The group of transistors dissipates an amount of electrical energy when driving the bus to a logic level opposite to a logic level present on the bus in an immediate preceding time slot. The group of transistors is arranged to dump another amount of electrical energy. Dumping of the other amount of electrical energy is responsive to driving the bus to a logic level that is the same as present on the bus in an immediate preceding time slot. The dumped amount of electrical energy is equivalent to the amount of energy dissipated by the transistors when transitioning the bus to a different logic level. Other aspects are also described.

Data bus driver with electrical energy dump

A hearable has an audio amplifier circuit coupled to a speaker as a load. The amplifier circuit has current source drive, which attenuates electromagnetically coupled noise of the speaker. In other instances, the amplifier circuit has a first amplifier mode and a second amplifier mode, wherein in the first amplifier mode the amplifier circuit becomes configured to drive the speaker as a voltage source, and in the second amplifier mode the amplifier circuit becomes configured to drive the speaker as a current source. Control logic varies the amplifier circuit between i) the first amplifier mode for larger amplitudes of the audio signal, and ii) the second amplifier mode for smaller amplitudes of the audio signal. Other aspects are also described and claimed.

High output impedance audio amplifier for noise rejection

A power converter produces power at a greater voltage than provided by a power source, while drawing power from the power source, wherein the power converter has a variable input current limit or a variable input power limit. One or more audio amplifiers are configured into i) drawing power from the power source bypassing the power converter and ii) drawing power from the power converter, according to audio signal amplitude, during audio playback and in accordance with an audio signal being amplified. A load of each amplifier is determined for when the amplifier is drawing power from the power source bypassing the power converter. The variable input limit of the power converter is adjusted in accordance with the determined load, during the audio playback. Other aspects are also described and claimed.

Amplifier power converter input current/power limit adjustment using amplifier load determinations

An audio amplifier has an analog current source amplifier and a class D amplifier. The analog current source amplifier is active in a first mode to drive a speaker when an audio signal has smaller amplitude. The class D amplifier is active in a second mode to drive the speaker when the audio signal has larger amplitude. Other aspects are also described and claimed.

Current-source switching hybrid audio amplifier

An audio amplifier has a first H bridge and a second H bridge, to drive a speaker as a load. The second H bridge drives the speaker through resistors for increased output impedance. Control logic operates the first H bridge as a class D amplifier for larger amplitudes of audio signal, and operates the second H bridge as a class D amplifier for smaller amplitudes of audio signal. Other aspects are also described and claimed.

Increased output impedance switching amplifier and low-side recycle mode

A power converter provides a first output voltage and a second output voltage in accordance with a control input, wherein the first output voltage is higher than the second output voltage. A switch that is series coupled between i) an energy reservoir node and ii) a power supply node or a power return node. A charge maintenance circuit is coupled to the energy reservoir node, and when the switch is closed can maintain a selected amount of charge in or a selected voltage across an energy reservoir element that may be coupled to the energy reservoir node. Other aspects are also described and claimed.

Electrical power converter and detachable energy storage reservoir

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.

Interference-insensitive capacitive displacement sensing

An analog to digital conversion circuit receives a transducer output signal and outputs a data bitstream, where a latch or flip flop has an input that receives a clock signal. An AC-DC power converter receives the clock signal and produces a DC voltage which may power the analog to digital conversion circuit. The AC-DC power converter has a rectifier, an energy store and a voltage regulator, charge pump or filter, which draws power from the energy store to produce the DC voltage. A control circuit delays replenishment of the energy store by the rectified clock signal, responsive to the clock signal. Other embodiments are also described and claimed.

Digital transducer circuit

A speaker assembly including a sound radiating surface suspended over a magnet assembly, a suspension member for suspending the sound radiating surface over the magnet assembly, a voice coil extending from a bottom side of the sound radiating surface, and a capacitive displacement sensor for sensing a movement of the sound radiating surface. The capacitive displacement sensor including a first conductive plate fixedly positioned over the sound radiating surface and a second conductive plate coupled to the sound radiating surface and vertically aligned with the first conductive plate, and wherein the second conductive plate is confined to an area that is entirely radially inward of the voice coil.

Capacitive sensing of a moving-coil structure with an inset plate

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.

Sensor assembly for measuring diaphragm displacement and temperature in a micro speaker

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.

Grounding circuit for alternate audio plug designs

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.

Charge pump-based split-rail supply generation

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.

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San Francisco, CA, United States of America

Roderick Brian Hogan