Noise cancellation for microphone-speaker combinations using combined speaker amplifier and reference sensing
AssigneeApple Inc.
InventorsTimothy M. Johnson, Lawrence F. Heyl
Life of this patent
Estimating the term…
Abstract
An audio host device has a connector having a speaker contact, a microphone contact, and a reference contact. The reference contact is shared by a microphone and a speaker. The reference contact is also directly coupled to a power return plane of the audio host device. A difference amplifier is provided, having a first cold input, a second cold input, and hot input. The first cold input is coupled to an output of the speaker amplifier, while the second cold input is coupled a sense point for the reference contact. The hot input is coupled to the microphone contact. Other embodiments are also described and claimed.
Claims29
An audio host device comprising:
- an electrical interface having a speaker contact, a microphone contact, and a reference contact, the reference contact to be shared by a microphone and a speaker, the reference contact being directly coupled to a power return plane of the audio host device;
- a speaker amplifier having an output that is coupled to the speaker contact;
- and
- a difference amplifier having a first cold input, a second cold input, and a hot input, the first cold input is coupled to an output of the speaker amplifier, the second cold input being coupled a sense point for the reference contact, and the hot input being coupled to the microphone contact.
A method for operating an audio host device having a headset electrical interface, comprising:
- sensing an output of a speaker amplifier, wherein the output is coupled to a speaker contact of the headset electrical interface;
- sensing a reference contact of the headset electrical interface, wherein the reference contact is shared by a speaker and a microphone of a microphone-speaker combination that are coupled to the headset electrical interface;
- combining the sensed speaker amplifier output and the sensed reference at a cold side input of a difference amplifier;
- sensing a microphone contact of the headset electrical interface at a hot side input of the difference amplifier;
- and
- adjusting a proportion of one or both of the sensed speaker amplifier output and the sensed reference, that have been combined at the cold side input.
A portable audio host device comprising:
- a host connector having a speaker contact, a microphone contact, and a reference contact, the reference contact to be shared by a microphone and a speaker, the reference contact being directly coupled to a power return plane of the audio host device;
- a speaker amplifier having an output that is coupled to the speaker contact of the connector;
- a first variable gain component amplifier having an input coupled to the output of the speaker amplifier;
- a second variable gain component amplifier having an input coupled to a sense point for the reference contact;
- a difference amplifier having a cold side input coupled to an output of the first component amplifier and an output of the second component amplifier, and a hot side input being coupled to the microphone contact;
- and
- a controller coupled to the first and second component amplifiers, wherein the controller is to set the gain of the first and second component amplifiers to reduce noise at an output of the difference amplifier.
Dependencies are inferred from the claim text.