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.

公开(公告)号：US11799426B2

公开(公告)日：2023-10-24

申请号：US17537619

申请日：2021-11-30

Applicant: Cirrus Logic International Semiconductor Ltd.

Inventor： Johnny Klarenbeek ,  David P. Singleton ,  Morgan T. Prior ,  Jonathan T. Wigner ,  Christopher M. Dougherty ,  Qi Cai ,  Anindya Bhattacharya

IPC: H03F1/02 ,  H03F3/217 ,  H03F3/38

CPC classification number: H03F1/0233 ,  H03F3/217 ,  H03F2200/03 ,  H03F2200/105

Abstract: Class D amplifier circuitry comprising: input buffer circuitry configured to receive a first digital input signal modulated according to a first modulation scheme in which the digital input signal can take a first plurality N of discrete signal levels; analog modulator circuitry configured to generate an analog modulated signal based on an analog output signal output by the input buffer circuitry; and quantizer circuitry configured to generate an output signal based on the analog modulated signal, wherein the output signal is modulated according to a second modulation scheme in which the output signal can take a second plurality M of discrete signal levels, wherein the second plurality M is greater than the first plurality N.

公开(公告)号：US20250147713A1

公开(公告)日：2025-05-08

申请号：US18500224

申请日：2023-11-02

Applicant: CIRRUS LOGIC INTERNATIONAL SEMICONDUCTOR LTD.

Inventor： Gaofeng Fan ,  Qi Cai ,  John B. Bowlerwell ,  Richard Turkson ,  Anindya Bhattacharya ,  Bhoodev Kumar

IPC: G06F3/16

Abstract: Circuit techniques reduce or prevent audible artifacts in a Universal Audio Jack (UAJ) interface circuit, improving handling of mis-configuration/mis-attachment of devices. The interface includes at least one terminal for accepting an audio input signal or providing an audio line output signal coupled to an input or output of a first audio circuit. The first audio circuit operates from a low voltage domain and receives the audio input signal or provides the audio line output signal. A second circuit operates from a higher voltage domain and a switching circuit couples the at least one terminal to the second circuit. The output is slew-rate controlled to control a transition time of the output, so that audible artifacts in the audio input signal or the audio line output signal that could be generated by the switching circuit connecting the second circuit to the at least one terminal are avoided.

公开(公告)号：US20190037327A1

公开(公告)日：2019-01-31

申请号：US16046943

申请日：2018-07-26

Applicant: CIRRUS LOGIC INTERNATIONAL SEMICONDUCTOR LTD.

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

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

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.