Systems and methods for reducing audio artifacts from switching between paths of a multi-path signal processing system

Patent metadata

Field	Value
Publication number	US-9880802-B2
Application number	US-201615003371-A
Country	US
Kind code	B2
Filing date	Jan 21, 2016
Priority date	Jan 21, 2016
Publication date	Jan 30, 2018
Grant date	Jan 30, 2018

Abstract

A processing path may include a controller and a plurality of processing paths including a first processing path and a second processing path. The first path may be configured to generate a first digital signal based on an analog input signal and the second path may be configured to generate a second digital signal based on the analog input signal, wherein the first path has a lower gain and a higher noise floor than the second path. The controller may be configured to determine that a transition between the first path and the second path needs to occur based on the analog input signal crossing a threshold or a prediction that the input signal will cross the threshold and in response to determining the transition between the first path and the second path needs to occur, blend the transition during or near zero cross points of the analog input signal.

First claim

What is claimed is:

1. A processing system comprising:
a plurality of processing paths including a first processing path and a second processing path, wherein:
the first processing path is configured to generate a first digital signal based on an analog input signal; and
the second processing path is configured to generate a second digital signal based on the analog input signal; and
wherein the first processing path has a lower gain and a higher noise floor than the second processing path;

a controller configured to:
determine that a transition between the first processing path and the second processing path needs to occur based on the analog input signal crossing a threshold or a prediction that the input signal will cross the threshold;
in response to determining the transition between the first processing path and the second processing path needs to occur, blend the transition during or near zero cross points of the analog input signal.

2. The processing system of claim 1 comprising:
a controller further configured to, transition continuously or in a plurality of steps the digital output signal between the first digital signal and the second digital signal, wherein a rate of the transition is based on the magnitude of the analog input signal, and such that during such transition, the digital output signal is a weighted average of the first digital signal and the second digital signal, wherein a weight of the second digital signal relative to a weight of the first digital signal increases or decreases during the transition.

3. The processing system of claim 1 , wherein:
the first processing path comprises a first analog front end and a first digital processing subsystem having a first analog-to-digital converter, wherein the first analog front end is configured to amplify the analog input signal in order to generate a first amplified analog signal and the first analog-to-digital converter is configured to convert the first amplified analog signal into the first digital signal; and
the second processing path comprises a second analog front end and a second digital processing subsystem having a second analog-to-digital converter, wherein the second analog front end is configured to amplify the analog input signal to generate a second amplified analog signal and the second analog-to-digital converter is configured to convert the second amplified analog signal into the second digital signal, and further wherein a magnitude of a gain of the second analog front end is substantially larger than a magnitude of a gain of the first analog front end.

4. The processing system of claim 1 , wherein the processing system is an audio processing system, and the analog input signal and the digital output signal are each an audio signal.

5. The processing system of claim 1 wherein the controller is further configured to transition continuously or in a plurality of steps the digital output signal between the first digital signal and the second digital signal, wherein a rate of the transition is based on the magnitude of the analog input signal, and such that during such transition, the digital output signal is a weighted average of the first digital signal and the second digital signal, wherein a weight of the second digital signal relative to a weight of the first digital signal increases or decreases during the transition.

6. The processing system of claim 1 , wherein the controller is further configured to transition continuously or in a plurality of steps the digital output signal between the first digital signal and the second digital signal, wherein each of the plurality of steps occurs responsive to the input signal crossing the threshold or the prediction that the input signal will cross the threshold.

7. The processing system of claim 1 , wherein the controller is further configured to predict the analog input signal crossing the threshold responsive to a magnitude of the analog input signal increasing above a second threshold less than the threshold.

8. The processing system of claim 1 , wherein the controller is further configured to predict the analog input signal crossing the threshold responsive to a magnitude of the analog input signal decreasing below a second threshold greater than the predetermined threshold magnitude.

9. The processing system of claim 1 , wherein the controller is further configured to predict the analog input signal crossing the threshold by:
tracking signal peaks of the analog input signal;
extrapolating from the signal peaks a future value of a magnitude of the analog input signal; and
predicting that the magnitude of the analog input signal will cross the threshold based on the future value.

10. The processing system of claim 1 , wherein the controller is further configured to predict the analog input signal crossing the threshold by:
tracking a signal envelope of the analog input signal;
extrapolating from the envelope a future value of the magnitude of the analog input signal; and
predicting that the analog input signal will cross the threshold based on the future value.

11. The processing system of claim 1 , wherein the controller is further configured to determine that the transition needs to occur responsive to a magnitude of audio input signal lacking a persistent pattern of magnitude relative to the predetermined threshold magnitude.

12. A method comprising:
generating a first digital signal with a first processing path based on an analog input signal;
generating a second digital signal with a second processing path based on the analog input signal, wherein the first processing path has a lower gain and a higher noise floor than the second processing path;
determining that a transition between the first processing path and the second processing path needs to occur based on the analog input signal crossing a threshold or a prediction that the input signal will cross the threshold;
in response to determining the transition between the first processing path and the second processing path needs to occur, blending the transition during or near zero cross points of the analog input signal.

13. The method of claim 12 , further comprising transitioning continuously or in a plurality of steps the digital output signal between the first digital signal and the second digital signal, wherein a rate of the transition is based on the magnitude of the analog input signal, and such that during such transition, the digital output signal is a weighted average of the first digital signal and the second digital signal, wherein a weight of the second digital signal relative to a weight of the first digital signal increases or decreases during the transition.

14. The method of claim 12 , wherein:
the first processing path comprises a first analog front end and a first digital processing subsystem having a first analog-to-digital converter, wherein the first analog front end is configured to amplify the analog input signal in order to generate a first amplified analog signal and the first analog-to-digital converter is configured to convert the first amplified analog signal into the first digital signal; and
the second processing path comprises a second analog front end and a second digital processing subsystem having a second analog-to-digital converter, wherein the second analog front end is configured to amplify the analog input signal to generate a second amplified analog signal and the second analog-to-digital converter is configured to convert the second amplified analog signal into the second digital signal, and further wherein a magnitude of a gain of the second analog front end is substantially large

Assignees

• Cirrus Logic Int Semiconductor Ltd
• Cirrus Logic Inc

Inventors

• Satoskar Aniruddha
• Allen Daniel J
• Schneider Edmund Mark
• Das Tejasvi
• He Ku
• Melanson John L

Classifications

• H03M1/0617 Primary

  characterised by the use of methods or means not specific to a particular type of detrimental influence · CPC title

• H03M1/12

  Analogue/digital converters ({H03M1/001 – } H03M1/10 take precedence) · CPC title

• H03M1/188 Primary

  Multi-path, i.e. having a separate analogue/digital converter for each possible range · CPC title

• G06F3/165 Primary

  Management of the audio stream, e.g. setting of volume, audio stream path · CPC title

• G10L25/09

  the extracted parameters being zero crossing rates · CPC title