Apple Inc.

Google Inc.

David C Breece, Iii

Nathan Alan Johanningsmeier

Cara S Yang

Chad Georges Seguin

Michael Asfaw

Roderick Brian Hogan

Leonardo Kusumo

Kavitha Srinivasan

Mahmoud R Amini

Daniel K Boothe

Cesar Lozano Villarreal

James Hollabaugh

Jonathan M Zweig

Kirill Kalinichev

Ruenjou Lu

Joseph C Curcio

Dirk Schmelzer

Nathan A Johanningsmeir

Adrien N Haage

Techniques, methods, systems, and other mechanisms for measuring the excursion of a speaker while being actively driven. Measuring excursion can involve attaching a flexible printed coil (FPC), including a sense coil, to the speaker, and monitoring an induced current as produced though the sense coil, and further detecting that violation of an excursion limit for the speaker may likely occur.

Inductive excursion sensing for audio transducers

Apparatus and methods for digital bus operation. In one embodiment, the digital bus is a bidirectional, time-division multiplexing (TDM) audio bus operation, and a bus technology is described that enables multi-drop (e.g., multiple device, multiple node, etc.) connectivity for real-time audio over a small form factor interface (e.g., as few as two (2) wires). Specifically, an exemplary tri-level signaling scheme provides bidirectional functionality, real-time clock edges, audio data, in a multi-drop topology in one implementation.

Methods and apparatus for multi-drop digital bus

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

An audio amplifier circuit that is to receive three audio channel signals as inputs. A first amplifier has a first pair of outputs one of which produces a first combination sum of the three audio channel signals, and the other produces a second, different combination sum of the three audio channel signals. A second amplifier has a second pair of outputs one of which produces a third, different combination sum of the three audio channel signals and the other produces a fourth, different combination sum of the three audio channel signals. Other embodiments are also described and claimed.

Audio amplifier circuit having inputs for three audio channels

An example method may be performed by a wearable computing device (WCD) that includes a bone conduction transducer (BCT). The method includes providing, to the BCT, an input signal that represents audio content. The method further includes sensing a time-varying voltage of the input signal and a time-varying current of the input signal. The method further includes determining an operating mode based on the time-varying voltage and the time-varying current. The method further includes processing the audio content according to the determined operating mode and using the processed audio content to continue providing the input signal to the BCT.

Closed loop audio processing for bone conduction transducer

Methods, systems, and apparatus for selectively communicating data and audio over a limited-size audio plug. A host device determines whether an audio accessory or a data communicating accessory is plugged therein via a signal, or lack thereof, communicated to the host device via the audio plug of the accessory. The host device then either communicates audio or data over the audio plug contacts that are typically used only for audio communication based on whether its connected to an audio accessory or data communicating accessory. An audio plug may also include a split-ring contact where multiple, independent contacts are formed in place of a single tip, ring, or sleeve contact. The split-ring contact may be used for communicating audio and/or data.

Data communications via limited length audio jack

A method for operating an audio system having multiple Class D audio amplifiers is described. An external oscillatory signal is coupled to the amplifiers, such that the switching frequencies of both of the amplifiers align with (e.g., are directly set to) a frequency of the external signal. An input level associated with an audio signal that is being amplified is detected, and the detected input level is compared to a threshold. When the comparison indicates that the input level is below a lower threshold, the frequency of the external oscillatory signal is raised, and when the comparison indicates that the input level is above an upper threshold, the frequency of the external oscillatory signal is lowered. Other embodiments are also described and claimed.

Class D amplifier with variable switching frequency

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 depletion mode transistor coupled between a first contact in an audio jack and ground, and a second depletion mode transistor coupled between a second contact in the audio jack and ground. The first depletion mode transistor and second depletion mode transistor may be p-channel transistors or n-channel transistors.

An audio source device has an audio connector to which an external load can be connected. An audio signal is amplified and then driven through the connector, wherein the amplification process uses feedback from the return pin of the connector. The return pin is directly connected to a ground break resistor circuit. The ground break resistor circuit is connected between the return pin of the audio connector and circuit ground. A determination is made as to whether the connected external load has a low impedance or a high impedance. When a low impedance load is detected, such as a headset, the ground break resistor circuit is essentially short-circuited. When a high impedance load is detected, the ground break resistor circuit is maintained and its value is set in accordance with the detected load. Other embodiments are also described.

Increasing ground noise rejection in audio systems

An electronic audio system that determines matching and non-matching speakers is disclosed. The electronic audio system includes a first speaker; a second speaker; and a comparator circuit. The comparator circuit is coupled to the first speaker and the second speaker to receive an input signal from both the first and second speaker. The comparator circuit is configured to determine if the first speaker and the second speaker are matching speakers or non-matching speakers, in which, the first and second speakers are matching speakers if they are common vendor speakers. Other embodiments are also described and claimed.

Growing community of inventors

Palo Alto, CA, United States of America

David C Breece, Iii