公开(公告)号：US10674296B2

公开(公告)日：2020-06-02

申请号：US16046943

申请日：2018-07-26

Applicant: CIRRUS LOGIC INTERNATIONAL SEMICONDUCTOR LTD.

Inventor： Anindya Battacharya ,  Bhoodev Kumar ,  John L. Melanson ,  Vivek Oppula ,  Anuradha Parsi ,  Qi Cai

IPC: H04R3/00 ,  H04R29/00 ,  H04R1/40 ,  G05F3/26

Abstract: An apparatus for biasing a plurality of microphones includes a sensing circuit that actively senses a local ground reference for each microphone. An intermediate stage receives a constant non-local reference voltage as an input and responsively provides a respective constant local reference signal (e.g., current) with respect to each of the actively sensed local ground references. For each microphone, a respective microphone bias block uses the respective constant local reference signal to generate a respective constant local microphone bias voltage to bias the microphone. For each microphone, a variable RC network uses the respective constant local reference current to generate a constant local reference voltage for the microphone. Each RC network is controllable in response to the respective actively sensed local ground reference to independently set the respective local microphone bias voltage. A sensing circuit may actively sense the local microphone bias voltages to control local microphone bias voltage generation.