Patents by Inventor Gautham Devendra Kamath
Gautham Devendra Kamath has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 9773490Abstract: A personal audio device, such as a wireless telephone, includes an adaptive noise canceling (ANC) circuit that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone is also provided proximate to the speaker to provide an error signal indicative of the effectiveness of the noise cancellation. A secondary path estimating adaptive filter is used to estimate the electro-acoustical path from the noise canceling circuit through the transducer so that source audio can be removed from the error signal. A level of the source audio with respect to the ambient audio is determined to determine whether the system may generate erroneous anti-noise and/or become unstable.Type: GrantFiled: June 9, 2015Date of Patent: September 26, 2017Assignee: CIRRUS LOGIC, INC.Inventors: Jeffrey Alderson, Jon D. Hendrix, Dayong Zhou, Antonio John Miller, Chin Yong, Gautham Devendra Kamath
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Patent number: 9721556Abstract: An adaptive noise canceling (ANC) circuit adaptively generates an anti-noise signal from a reference microphone signal that is injected into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone proximate the speaker provides an error signal. A secondary path estimating adaptive filter estimates the electro-acoustical path from the noise canceling circuit through the transducer so that source audio can be removed from the error signal. Tones in the source audio, such as remote ringtones, present in downlink audio during initiation of a telephone call, are detected by a tone detector using accumulated tone persistence and non-silence hangover counting, and adaptation of the secondary path estimating adaptive filter is halted to prevent adapting to the tones. Adaptation of the adaptive filters is then sequenced so any disruption of the secondary path adaptive filter response is removed before allowing the anti-noise generating filter to adapt.Type: GrantFiled: March 15, 2016Date of Patent: August 1, 2017Assignee: CIRRUS LOGIC, INC.Inventors: Dayong Zhou, Yang Lu, Jon D. Hendrix, Jeffrey Alderson, Antonio John Miller, Chin Yong, Gautham Devendra Kamath
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Patent number: 9711130Abstract: A personal audio device, such as a wireless telephone, includes an adaptive noise canceling (ANC) circuit that adaptively generates an anti-noise signal from a reference microphone signal that measures the ambient audio and an error microphone signal that measures the output of an output transducer plus any ambient audio at that location and injects the anti-noise signal at the transducer output to cause cancellation of ambient audio sounds. A processing circuit uses the reference and error microphone to generate the anti-noise signal, which can be generated by an adaptive filter operating at a multiple of the ANC coefficient update rate. Downlink audio can be combined with the high data rate anti-noise signal by interpolation. High-pass filters in the control paths reduce DC offset in the ANC circuits, and ANC coefficient adaptation can be halted when downlink audio is not detected.Type: GrantFiled: April 15, 2016Date of Patent: July 18, 2017Assignee: CIRRUS LOGIC, INC.Inventors: Jon D. Hendrix, Gautham Devendra Kamath, Nitin Kwatra, Ali Abdollahzadeh Milani, Jeffrey Alderson
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Patent number: 9646595Abstract: A personal audio device, such as a wireless telephone, includes an adaptive noise canceling (ANC) circuit that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone is also provided proximate the speaker to estimate an electro-acoustical path from the noise canceling circuit through the transducer. A processing circuit determines a degree of coupling between the user's ear and the transducer and adjusts the adaptive cancellation of the ambient sounds to prevent erroneous and possibly disruptive generation of the anti-noise signal if the degree of coupling lies either below or above a range of normal operating ear contact pressure.Type: GrantFiled: December 9, 2014Date of Patent: May 9, 2017Assignee: CIRRUS LOGIC, INC.Inventors: Ali Abdollahzadeh Milani, Gautham Devendra Kamath
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Patent number: 9502020Abstract: An adaptive noise canceling (ANC) circuit adaptively generates an anti-noise signal that is injected into the speaker or other transducer output to cause cancellation of ambient audio sounds. At least one microphone provides an error signal indicative of the noise cancellation at the transducer, and the adaptive filter is adapted to minimize the error signal. In order to prevent improper adaptation or instabilities in one or both of the adaptive filters, spikes are detected in the error signal by comparing the error signal or its rate of change to a threshold. Therefore, if the magnitude of the coefficient error is greater than a threshold value for an update, the update is skipped. Alternatively the step size of the updates may be reduced. Similar criteria can be applied to a filter modeling the secondary path, based on detection applied to both the source audio and the error signal.Type: GrantFiled: March 14, 2014Date of Patent: November 22, 2016Assignee: CIRRUS LOGIC, INC.Inventors: Ali Abdollahzadeh Milani, Jeffrey Alderson, Gautham Devendra Kamath, Yang Lu
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Publication number: 20160232887Abstract: A personal audio device, such as a wireless telephone, includes an adaptive noise canceling (ANC) circuit that adaptively generates an anti-noise signal from a reference microphone signal that measures the ambient audio and an error microphone signal that measures the output of an output transducer plus any ambient audio at that location and injects the anti-noise signal at the transducer output to cause cancellation of ambient audio sounds. A processing circuit uses the reference and error microphone to generate the anti-noise signal, which can be generated by an adaptive filter operating at a multiple of the ANC coefficient update rate. Downlink audio can be combined with the high data rate anti-noise signal by interpolation. High-pass filters in the control paths reduce DC offset in the ANC circuits, and ANC coefficient adaptation can be halted when downlink audio is not detected.Type: ApplicationFiled: April 15, 2016Publication date: August 11, 2016Inventors: Jon D. Hendrix, Gautham Devendra Kamath, Nitin Kwatra, Ali Abdollahzadeh Milani, Jeffrey Alderson
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Publication number: 20160196816Abstract: An adaptive noise canceling (ANC) circuit adaptively generates an anti-noise signal from a reference microphone signal that is injected into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone proximate the speaker provides an error signal. A secondary path estimating adaptive filter estimates the electro-acoustical path from the noise canceling circuit through the transducer so that source audio can be removed from the error signal. Tones in the source audio, such as remote ringtones, present in downlink audio during initiation of a telephone call, are detected by a tone detector using accumulated tone persistence and non-silence hangover counting, and adaptation of the secondary path estimating adaptive filter is halted to prevent adapting to the tones. Adaptation of the adaptive filters is then sequenced so any disruption of the secondary path adaptive filter response is removed before allowing the anti-noise generating filter to adapt.Type: ApplicationFiled: March 15, 2016Publication date: July 7, 2016Inventors: Dayong Zhou, Yang Lu, Jon D. Hendrix, Jeffrey Alderson, Antonio John Miller, Chin Yong, Gautham Devendra Kamath
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Patent number: 9368099Abstract: A personal audio device, such as a wireless telephone, includes noise canceling circuit that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone may also be provided proximate the speaker to measure the output of the transducer in order to control the adaptation of the anti-noise signal and to estimate an electro-acoustical path from the noise canceling circuit through the transducer. A processing circuit that performs the adaptive noise canceling (ANC) function also either adjusts the frequency response of the anti-noise signal with respect to the reference microphone signal, and/or by adjusting the response of the adaptive filter independent of the adaptation provided by the reference microphone signal.Type: GrantFiled: March 28, 2014Date of Patent: June 14, 2016Assignee: CIRRUS LOGIC, INC.Inventors: Jeffrey Alderson, Nitin Kwatra, Gautham Devendra Kamath, Ali Abdollahzadeh Milani, John L. Melanson
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Patent number: 9369798Abstract: A personal audio device, such as a headphone, includes an adaptive noise canceling (ANC) circuit that adaptively generates an anti-noise signal using one or more microphone signals that measure the ambient audio. The anti-noise signal is combined with source audio to provide an output for a speaker. The anti-noise signal causes cancellation of ambient audio sounds that appear in the microphone signals. A processing circuit uses the reference microphone to generate the anti-noise signal using one or more adaptive filters. The processing circuit also includes low-pass filters that remove quantization noise images at the output of the adaptive filter to reduce the dynamic range required at the output of the adaptive filter.Type: GrantFiled: March 12, 2013Date of Patent: June 14, 2016Assignee: CIRRUS LOGIC, INC.Inventors: Jeffrey Alderson, Jon D. Hendrix, Gautham Devendra Kamath
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Patent number: 9324311Abstract: An adaptive noise canceling (ANC) circuit adaptively generates an anti-noise signal from that is injected into the speaker or other transducer output to cause cancellation of ambient audio sounds. At least one microphone provides an error signal indicative of the noise cancellation at the transducer, and the coefficients of the adaptive filter are adapted to minimize the error signal. In order to prevent improper adaptation or instabilities in one or both of the adaptive filters, spikes are detected in the error signal by comparing the error signal to a threshold ambient noise average. Therefore, if the magnitude of the coefficient error is greater than a threshold value for an update, the update is skipped. Alternatively the step size of the updates may be reduced.Type: GrantFiled: March 14, 2014Date of Patent: April 26, 2016Assignee: CIRRUS LOGIC, INC.Inventors: Ali Abdollahzadeh Milani, Jeffrey Alderson, Gautham Devendra Kamath, Yang Lu
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Patent number: 9318094Abstract: A personal audio device, such as a wireless telephone, includes an adaptive noise canceling (ANC) circuit that adaptively generates an anti-noise signal from a reference microphone signal that measures the ambient audio and an error microphone signal that measures the output of an output transducer plus any ambient audio at that location and injects the anti-noise signal at the transducer output to cause cancellation of ambient audio sounds. A processing circuit uses the reference and error microphone to generate the anti-noise signal, which can be generated by an adaptive filter operating at a multiple of the ANC coefficient update rate. Downlink audio can be combined with the high data rate anti-noise signal by interpolation. High-pass filters in the control paths reduce DC offset in the ANC circuits, and ANC coefficient adaptation can be halted when downlink audio is not detected.Type: GrantFiled: March 7, 2012Date of Patent: April 19, 2016Assignee: CIRRUS LOGIC, INC.Inventors: Jon D. Hendrix, Gautham Devendra Kamath, Nitin Kwatra, Ali Abdollahzadeh Milani, Jeffrey Alderson
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Patent number: 9318090Abstract: An adaptive noise canceling (ANC) circuit adaptively generates an anti-noise signal from a reference microphone signal that is injected into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone proximate the speaker provides an error signal. A secondary path estimating adaptive filter estimates the electro-acoustical path from the noise canceling circuit through the transducer so that source audio can be removed from the error signal. Tones in the source audio, such as remote ringtones, present in downlink audio during initiation of a telephone call, are detected by a tone detector using accumulated tone persistence and non-silence hangover counting, and adaptation of the secondary path estimating adaptive filter is halted to prevent adapting to the tones. Adaptation of the adaptive filters is then sequenced so any disruption of the secondary path adaptive filter response is removed before allowing the anti-noise generating filter to adapt.Type: GrantFiled: December 28, 2012Date of Patent: April 19, 2016Assignee: CIRRUS LOGIC, INC.Inventors: Dayong Zhou, Yang Lu, Jon D. Hendrix, Jeffrey Alderson, Antonio John Miller, Chin Yong, Gautham Devendra Kamath
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Publication number: 20150269926Abstract: A personal audio device, such as a wireless telephone, includes an adaptive noise canceling (ANC) circuit that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone is also provided proximate to the speaker to provide an error signal indicative of the effectiveness of the noise cancellation. A secondary path estimating adaptive filter is used to estimate the electro-acoustical path from the noise canceling circuit through the transducer so that source audio can be removed from the error signal. A level of the source audio with respect to the ambient audio is determined to determine whether the system may generate erroneous anti-noise and/or become unstable.Type: ApplicationFiled: June 9, 2015Publication date: September 24, 2015Inventors: Jeffrey Alderson, Jon D. Hendrix, Dayong Zhou, Antonio John Miller, Chin Yong, Gautham Devendra Kamath
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Patent number: 9123321Abstract: A personal audio device, such as a wireless telephone, includes an adaptive noise canceling (ANC) circuit that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone is also provided proximate to the speaker to provide an error signal indicative of the effectiveness of the noise cancellation. A secondary path estimating adaptive filter is used to estimate the electro-acoustical path from the noise canceling circuit through the transducer so that source audio can be removed from the error signal. Adaptation of adaptive filters is sequenced so that update of their coefficients does not cause instability or error in the update. A level of the source audio with respect to the ambient audio can be determined to determine whether the system may generate erroneous anti-noise and/or become unstable.Type: GrantFiled: December 27, 2012Date of Patent: September 1, 2015Assignee: Cirrus Logic, Inc.Inventors: Jeffrey Alderson, Jon D. Hendrix, Dayong Zhou, Antonio John Miller, Chin Yong, Gautham Devendra Kamath
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Patent number: 9076431Abstract: A personal audio device, such as a wireless telephone, includes an adaptive noise canceling (ANC) circuit that generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cancel ambient audio sounds. A processing circuit implements one or more adaptive filters that control the generation of the anti-noise signal. At least one of the adaptive filters is partitioned into a first portion having a fixed frequency response and a second portion having a variable frequency response. The partitioned filter may be an adaptive filter that generates the anti-noise signal directly from the reference microphone signal. An error microphone may be provided to measure the ambient sounds and transducer output near the transducer, and a secondary path adaptive filter included to generate an error signal from the error microphone signal, which may be partitioned, alone or in combination.Type: GrantFiled: March 30, 2012Date of Patent: July 7, 2015Assignee: Cirrus Logic, Inc.Inventors: Gautham Devendra Kamath, Jon D. Hendrix
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Publication number: 20150092953Abstract: A personal audio device, such as a wireless telephone, includes an adaptive noise canceling (ANC) circuit that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone is also provided proximate the speaker to estimate an electro-acoustical path from the noise canceling circuit through the transducer. A processing circuit determines a degree of coupling between the user's ear and the transducer and adjusts the adaptive cancellation of the ambient sounds to prevent erroneous and possibly disruptive generation of the anti-noise signal if the degree of coupling lies either below or above a range of normal operating ear contact pressure.Type: ApplicationFiled: December 9, 2014Publication date: April 2, 2015Inventors: Ali Abdollahzadeh Milani, Gautham Devendra Kamath
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Patent number: 8948407Abstract: A personal audio device, such as a wireless telephone, includes noise canceling circuit that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone may also be provided proximate the speaker to measure the output of the transducer in order to control the adaptation of the anti-noise signal and to estimate an electro-acoustical path from the noise canceling circuit through the transducer. A processing circuit that performs the adaptive noise canceling (ANC) function also either adjusts the frequency response of the anti-noise signal with respect to the reference microphone signal, and/or by adjusting the response of the adaptive filter independent of the adaptation provided by the reference microphone signal.Type: GrantFiled: December 21, 2011Date of Patent: February 3, 2015Assignee: Cirrus Logic, Inc.Inventors: Jeffrey Alderson, Nitin Kwatra, Gautham Devendra Kamath, Ali Abdollahzadeh Milani, John L. Melanson
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Patent number: 8908877Abstract: A personal audio device, such as a wireless telephone, includes an adaptive noise canceling (ANC) circuit that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone is also provided proximate the speaker to estimate an electro-acoustical path from the noise canceling circuit through the transducer. A processing circuit determines a degree of coupling between the user's ear and the transducer and adjusts the adaptive cancellation of the ambient sounds to prevent erroneous and possibly disruptive generation of the anti-noise signal if the degree of coupling lies either below or above a range of normal operating ear contact pressure.Type: GrantFiled: December 2, 2011Date of Patent: December 9, 2014Assignee: Cirrus Logic, Inc.Inventors: Ali Abdollahzadeh Milani, Gautham Devendra Kamath
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Publication number: 20140211953Abstract: A personal audio device, such as a wireless telephone, includes noise canceling circuit that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone may also be provided proximate the speaker to measure the output of the transducer in order to control the adaptation of the anti-noise signal and to estimate an electro-acoustical path from the noise canceling circuit through the transducer. A processing circuit that performs the adaptive noise canceling (ANC) function also either adjusts the frequency response of the anti-noise signal with respect to the reference microphone signal, and/or by adjusting the response of the adaptive filter independent of the adaptation provided by the reference microphone signal.Type: ApplicationFiled: March 28, 2014Publication date: July 31, 2014Applicant: Cirrus Logic, Inc.Inventors: Jeffrey Alderson, Nitin Kwatra, Gautham Devendra Kamath, Ali Abdollahzadeh Milani, John L. Melanson
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Patent number: 8643340Abstract: An integrated circuit (IC) having an internal power supply voltage step down circuit provides efficiency while requiring a minimum of external terminals. In a first operating mode, a storage capacitor is charged from the power supply return of a group of circuits, while the group of circuits is powered from an input power supply voltage provided to the IC. In a second operating mode, the group of circuits is powered from the storage capacitor. The step-down circuit provides for halving the input power supply voltage, but multiple storage capacitors and additional operating modes can be provided for voltage division by greater factors. A sensing circuit can be employed to sense the voltage across the storage capacitor(s) and in response, select the operating mode, providing hysteretic control of the voltage supplied to the group of circuits.Type: GrantFiled: September 29, 2009Date of Patent: February 4, 2014Assignee: Cirrus Logic, Inc.Inventor: Gautham Devendra Kamath