Differential mode noise cancellation with active real-time control for microphone-speaker combinations used in two way audio communications

  • US 20110033064A1
  • Filed: 08/04/2009
  • Published: 02/10/2011
  • Est. Priority Date: 08/04/2009
  • Status: Active Grant
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First Claim
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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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