Patent ID: 8270630
Filing Date: 2012-09-18
Classification: H03G,H04R

Abstract:
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 programmable gain amplifier, PGA, having a signal input coupled to a sense point for the reference contact; a first difference amplifier having a pair of inputs, one of the pair of inputs being coupled to the microphone contact, and the other being coupled to a signal output of the PGA through a first gain stage; a second difference amplifier having a pair of inputs, one of the pair of inputs being coupled to the microphone contact, and the other being coupled to the output of the PGA through a second gain stage having a different gain than the first gain stage; a third difference amplifier having a pair of inputs, one of the pair of inputs being coupled to the microphone contact, and the other being coupled to the output of the PGA through a third gain stage having a gain in between that of the first and second gain stages; and a controller having an output coupled to a control input of the PGA, the controller to monitor outputs of the first and second difference amplifiers and change a gain setting of the PGA.