Differential mode noise cancellation with active real-time control for microphone-speaker combinations used in two way audio communications
First Claim
1. 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 difference amplifier having a first input and a second input, the second input being coupled to the microphone contact;
a variable attenuator circuit having an input coupled to a sense point for the reference contact and an output coupled to the first input of the difference amplifier, wherein the variable attenuator circuit has a plurality of different attenuation states; and
a controller having an output coupled to control the variable attenuator to set any one of the different attenuation states.
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Accused Products
Abstract
An audio host device has an electrical interface 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 cold input and a hot input. The hot input is coupled to the microphone contact. A variable attenuator circuit is also provided having an input coupled to receive a signal from a sense point for the reference contact, and an output coupled to the cold input of the difference amplifier. A controller has an output coupled to control the variable attenuator. Other embodiments are also described and claimed.
314 Citations
20 Claims
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1. An audio host device comprising:
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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 difference amplifier having a first input and a second input, the second input being coupled to the microphone contact; a variable attenuator circuit having an input coupled to a sense point for the reference contact and an output coupled to the first input of the difference amplifier, wherein the variable attenuator circuit has a plurality of different attenuation states; and a controller having an output coupled to control the variable attenuator to set any one of the different attenuation states. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for operating an audio host device, comprising:
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playing a super-audible tone through a speaker contact of a headset connector in the audio host device, while a headset having a microphone is coupled to the connector; measuring output of a microphone signal difference amplifier in the audio host device, while the headset is coupled to the connector and the super-audible tone is playing; and attenuating a signal that is input to the amplifier based on the measurement by an amount that reduces presence of the super-audible tone at the output of the amplifier. - View Dependent Claims (11, 12, 13, 14)
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15. A portable audio host device comprising:
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a headset connector having a speaker contact, a microphone contact, and a reference contact, the reference contact to be shared by a microphone and an speaker; a difference amplifier having a first input and a second input, the second input being coupled to the microphone contact; a variable voltage attenuator having an input coupled to receive a signal from a sense point for the reference contact, and an output coupled to the first input of the difference amplifier; and a controller having an output coupled to control the variable attenuator. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification