Patents by Inventor Tejasvi Das
Tejasvi Das 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: 9998823Abstract: In accordance with embodiments of the present disclosure, a control circuit may be configured to, responsive to an indication to switch between gain modes of a signal path having an analog path portion and a digital signal path portion, switch a selectable analog gain of the analog path portion between a first analog gain and a second analog gain, switch a selectable digital gain of the digital signal path portion between a first digital gain and a second digital gain, wherein the product of the first analog gain and the first digital gain is approximately equal to the product of the second analog gain and the second digital gain, and control an analog response of the signal path to reduce the occurrence of audio artifacts present in the output signal as a result of the switch between gain modes of the signal path. A signal path may have an analog path portion and a digital signal path portion.Type: GrantFiled: October 6, 2014Date of Patent: June 12, 2018Assignee: Cirrus Logic, Inc.Inventors: Ku He, Tejasvi Das, John L. Melanson, Anniruddha Satoskar
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Publication number: 20180159488Abstract: An amplifier may include a first stage configured to receive an input signal at an amplifier input and generate an intermediate signal which is a function of the input signal, and a final output stage configured to generate an output signal which is a function of the intermediate signal at an amplifier output, and a signal feedback network coupled between the amplifier output and input. The final output stage may be switchable among a plurality of modes including at least a first mode in which the final output stage generates the output signal as a modulated output signal which is a function of the intermediate signal, and a second mode in which the final output stage generates the output signal as an unmodulated output signal which is a function of the intermediate signal. Structure of the feedback network and the first stage may remain static when switching between modes.Type: ApplicationFiled: January 31, 2018Publication date: June 7, 2018Applicant: Cirrus Logic International Semiconductor Ltd.Inventors: Xin ZHAO, Tejasvi DAS, Xiaofan FEI, Alan Mark MORTON
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Publication number: 20180152174Abstract: A variable resistor may be coupled between a reference voltage source and components of an integrated circuit to reduce issues relating to thermal noise from a reference voltage signal generated by the reference voltage source. The variable resistor may be set to a low level during a first time period and a high level during a second time period, in which the time periods correspond to a sampling period of a switched-capacitor circuit. The low resistance time period may allow quick settling of an input reference voltage signal, whereas the high resistance time period may reduce a bandwidth of noise on a sampling capacitor coupled to the reference voltage signal. The variable resistor and switched-capacitor network may be used in an analog-to-digital converter (ADC), such as in audio circuits.Type: ApplicationFiled: November 30, 2016Publication date: May 31, 2018Applicant: Cirrus Logic International Semiconductor Ltd.Inventors: Ramin Zanbaghi, Tejasvi Das, John L. Melanson, Axel Thomsen
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Patent number: 9967665Abstract: An analog signal path portion of a signal path may have: (i) an audio input for receiving an analog signal, an audio output for providing an output signal, and a selectable analog gain, and may be configured to generate the output signal based on the analog signal and in conformity with the selectable analog gain; and (ii) a digital path portion having a selectable digital gain and configured to receive a digital input signal and convert the digital input signal into the analog signal in conformity with the selectable digital gain. A control circuit may be configured to modify the digital and analog gains in response to an indication to switch between gain modes of the signal path, determine a noise floor of an audio signal comprising the digital input signal or a signal derived therefrom, and control modification of the digital and analog gains based on the noise floor.Type: GrantFiled: October 5, 2016Date of Patent: May 8, 2018Assignee: Cirrus Logic, Inc.Inventors: Tejasvi Das, Ku He, John L. Melanson
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Patent number: 9955254Abstract: In accordance with embodiments of the present disclosure, a method may include receiving a digital input signal at a first integrated circuit from a second integrated circuit, receiving a supply voltage at the first integrated circuit from the second integrated circuit, generating an analog output signal from the digital input signal, predicting a distortion of the analog output signal based on the digital input signal and the supply voltage, and controlling a gain applied to at least one of the digital input signal and the analog output signal based on the predicting.Type: GrantFiled: November 25, 2015Date of Patent: April 24, 2018Assignee: Cirrus Logic, Inc.Inventors: Tejasvi Das, John L. Melanson
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Publication number: 20180098149Abstract: An analog signal path portion of a signal path may have: (i) an audio input for receiving an analog signal, an audio output for providing an output signal, and a selectable analog gain, and may be configured to generate the output signal based on the analog signal and in conformity with the selectable analog gain; and (ii) a digital path portion having a selectable digital gain and configured to receive a digital input signal and convert the digital input signal into the analog signal in conformity with the selectable digital gain. A control circuit may be configured to modify the digital and analog gains in response to an indication to switch between gain modes of the signal path, determine a noise floor of an audio signal comprising the digital input signal or a signal derived therefrom, and control modification of the digital and analog gains based on the noise floor.Type: ApplicationFiled: October 5, 2016Publication date: April 5, 2018Applicant: Cirrus Logic International Semiconductor Ltd.Inventors: Tejasvi DAS, Ku HE, John L. MELANSON
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Publication number: 20180091102Abstract: An amplifier may include a first stage configured to receive an input signal at an amplifier input and generate an intermediate signal which is a function of the input signal, and a final output stage configured to generate an output signal which is a function of the intermediate signal at an amplifier output, and a signal feedback network coupled between the amplifier output and input. The final output stage may be switchable among a plurality of modes including at least a first mode in which the final output stage generates the output signal as a modulated output signal which is a function of the intermediate signal, and a second mode in which the final output stage generates the output signal as an unmodulated output signal which is a function of the intermediate signal. Structure of the feedback network and the first stage may remain static when switching between modes.Type: ApplicationFiled: September 27, 2016Publication date: March 29, 2018Applicant: Cirrus Logic International Semiconductor Ltd.Inventors: Xin ZHAO, Tejasvi DAS, Xiaofan FEI, Alan Mark MORTON
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Patent number: 9929703Abstract: An amplifier may include a first stage configured to receive an input signal at an amplifier input and generate an intermediate signal which is a function of the input signal, and a final output stage configured to generate an output signal which is a function of the intermediate signal at an amplifier output, and a signal feedback network coupled between the amplifier output and input. The final output stage may be switchable among a plurality of modes including at least a first mode in which the final output stage generates the output signal as a modulated output signal which is a function of the intermediate signal, and a second mode in which the final output stage generates the output signal as an unmodulated output signal which is a function of the intermediate signal. Structure of the feedback network and the first stage may remain static when switching between modes.Type: GrantFiled: September 27, 2016Date of Patent: March 27, 2018Assignee: Cirrus Logic, Inc.Inventors: Xin Zhao, Tejasvi Das, Xiaofan Fei, Alan Mark Morton
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Patent number: 9917557Abstract: A method for offset calibration may include decoupling a modulator input of a first path from a first stage output, coupling a second path output to the modulator input, applying a common-mode voltage to a second path input, receiving a calibration signal from the modulator output generated in response to the common-mode voltage, and modifying one or more parameters of the modulator to compensate for an offset between the first path and the second path indicated by the calibration signal.Type: GrantFiled: April 17, 2017Date of Patent: March 13, 2018Assignee: Cirrus Logic, Inc.Inventors: Lei Zhu, Xin Zhao, Tejasvi Das, Alan Mark Morton, Xiaofan Fei
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Publication number: 20180062583Abstract: A dynamic common reference input (CMRI) signal may be provided to an operational amplifier, or “op-amp,” in an amplifier system to reduce the common mode ripple of the fully-differential op-amp, while adding little or no noise in the amplifier system. The dynamic CMRI signal may be controlled such that a common-mode component of two amplifier input nodes of the operational amplifier is made approximately independent of two input signals received at two system input nodes of the amplifier system. An amplifier system with the dynamic CMRI may be used in class-D amplifiers, such as amplifiers for audio systems that generate output for headphones or speakers.Type: ApplicationFiled: January 27, 2017Publication date: March 1, 2018Applicant: Cirrus Logic International Semiconductor Ltd.Inventors: Xin Zhao, Tejasvi Das, Hossein Mirzaie, Lei Zhu, Xiaofan Fei
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Patent number: 9880802Abstract: 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.Type: GrantFiled: January 21, 2016Date of Patent: January 30, 2018Assignee: Cirrus Logic, Inc.Inventors: Aniruddha Satoskar, Daniel J. Allen, Edmund Mark Schneider, Tejasvi Das, Ku He, John L. Melanson
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Publication number: 20170374456Abstract: A method may be provided for powering up or down a playback path comprising a digital-to-analog converter (DAC) for generating a non-ground-centered analog intermediate voltage centered at a common-mode voltage and coupled to a driver for generating a ground-centered playback path output voltage at an output of the driver wherein the output of the driver is clamped via a finite impedance to a ground voltage. The method may include transitioning continuously or in a plurality of discrete steps the analog intermediate voltage from an initial voltage to the common-mode voltage such that the transitioning is substantially inaudible at the output of the driver. A method for operating an output clamp of an output driver stage of a playback path may include transitioning continuously or in a plurality of discrete steps an impedance of the output clamp in order to match an output offset of the output driver stage in order to minimize audio artifacts appearing at an output of the output driver stage.Type: ApplicationFiled: June 28, 2016Publication date: December 28, 2017Applicant: Cirrus Logic International Semiconductor Ltd.Inventors: Tejasvi DAS, Anand ILANGO
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Patent number: 9854357Abstract: A method may be provided for powering up or down a playback path comprising a digital-to-analog converter (DAC) for generating a non-ground-centered analog intermediate voltage centered at a common-mode voltage and coupled to a driver for generating a ground-centered playback path output voltage at an output of the driver wherein the output of the driver is clamped via a finite impedance to a ground voltage. The method may include transitioning continuously or in a plurality of discrete steps the analog intermediate voltage from an initial voltage to the common-mode voltage such that the transitioning is substantially inaudible at the output of the driver. A method for operating an output clamp of an output driver stage of a playback path may include transitioning continuously or in a plurality of discrete steps an impedance of the output clamp in order to match an output offset of the output driver stage in order to minimize audio artifacts appearing at an output of the output driver stage.Type: GrantFiled: June 28, 2016Date of Patent: December 26, 2017Assignee: Cirrus Logic, Inc.Inventors: Tejasvi Das, Anand Ilango
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Patent number: 9831843Abstract: An audio playback path of an audio apparatus includes a digital modulator, a digital-to-analog converter (DAC), and a power amplifier. The digital modulator receives a playback signal corresponding to playback audio content and generates a digital input signal in accordance with the playback signal. The DAC receives the audio input signal and generates an analog preamplifier signal. The power amplifier generates an audio output signal in accordance with the preamplifier signal and an analog attenuation determined by the analog attenuation signal.Type: GrantFiled: March 11, 2014Date of Patent: November 28, 2017Assignee: Cirrus Logic, Inc.Inventors: Tejasvi Das, Bharath Kumar Thandri, Anand Ilango, Aniruddha Satoskar, Daniel John Allen, Xiaofan Fei
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Patent number: 9813814Abstract: In accordance with embodiments of the present disclosure, an apparatus for providing an output signal to an audio transducer may include a signal path and a control circuit. The signal path may include an analog signal path portion having an audio input for receiving an analog signal, an audio output for providing an output signal, and a selectable analog gain, and configured to generate the output signal based on the analog signal and in conformity with the selectable analog gain and a digital path portion having a selectable digital gain and configured to receive a digital input signal and convert the digital input signal into the analog signal in conformity with the selectable digital gain. The control circuit may be configured to determine a spectral content of a signal indicative of the output signal and change the selectable digital gain and the selectable analog gain based on the spectral content.Type: GrantFiled: August 23, 2016Date of Patent: November 7, 2017Assignee: Cirrus Logic, Inc.Inventors: Aniruddha Satoskar, Tejasvi Das, Ku He
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Publication number: 20170310288Abstract: An audio amplifier circuit for providing an output signal to an audio transducer may include a power amplifier and a control circuit. The power amplifier may include an audio input for receiving an audio input signal, an audio output for generating the output signal based on the audio input signal, and a power supply input for receiving a power supply voltage, wherein the power supply voltage is variable among at least a first supply voltage and a second supply voltage greater than the first supply voltage. The control circuit may be configured to predict, based on one or more characteristics of a signal indicative of the output signal, an occurrence of a condition for changing the power supply voltage, and responsive to predicting the occurrence of the condition, change, at an approximate zero crossing of the signal indicative of the output signal, the power supply voltage.Type: ApplicationFiled: April 22, 2016Publication date: October 26, 2017Applicant: Cirrus Logic International Semiconductor Ltd.Inventors: Tejasvi DAS, John L. MELANSON, Eric J. KING
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Publication number: 20170212721Abstract: 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.Type: ApplicationFiled: January 21, 2016Publication date: July 27, 2017Applicant: Cirrus Logic International Semiconductor Ltd.Inventors: Aniruddha Satoskar, Daniel J. Allen, Edmund Mark Schneider, Tejasvi Das, Ku He, John L. Melanson
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Patent number: 9692444Abstract: In accordance with embodiments of the present disclosure, a method of neutralizing voltage kickback associated with a reference buffer of a switched capacitor based data converter having a first switched capacitor coupled to an output node of the reference buffer wherein the first switched capacitor comprises at least one first capacitor and at least one first switch may be provided. The method may include coupling a passive network to the output node of the reference buffer in response to a presence of a condition for encountering the voltage kickback in order to create an approximately equal and opposite voltage kickforward by the passive network to at least partially neutralize the voltage kickback.Type: GrantFiled: June 30, 2016Date of Patent: June 27, 2017Assignee: Cirrus Logic, Inc.Inventors: Tejasvi Das, John L. Melanson, Ramin Zanbaghi
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Patent number: 9680488Abstract: In accordance with embodiments of the present disclosure, a processing system may include a plurality of processing paths including a first processing path and a second processing path, a digital-to-analog stage output, and a controller. The first processing path may include a first digital-to-analog converter for converting the digital input signal into a first intermediate analog signal, the first digital-to-analog converter configured to operate in a high-power state and a low-power state. The second processing path may include a second digital-to-analog converter for converting a digital input signal into a second intermediate analog signal. The digital-to-analog stage output may be configured to generate an analog signal comprising a sum of the first intermediate analog signal and the second intermediate analog signal. The controller may be configured to operate the first digital-to-analog converter in the lower-power state when a magnitude of the digital input signal is below a threshold magnitude.Type: GrantFiled: February 23, 2016Date of Patent: June 13, 2017Assignee: Cirrus Logic, Inc.Inventors: Tejasvi Das, John L. Melanson, John C. Tucker, Xiaofan Fei
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Publication number: 20170150257Abstract: In accordance with embodiments of the present disclosure, a method may include receiving a digital input signal at a first integrated circuit from a second integrated circuit, receiving a supply voltage at the first integrated circuit from the second integrated circuit, generating an analog output signal from the digital input signal, predicting a distortion of the analog output signal based on the digital input signal and the supply voltage, and controlling a gain applied to at least one of the digital input signal and the analog output signal based on the predicting.Type: ApplicationFiled: November 25, 2015Publication date: May 25, 2017Applicant: Cirrus Logic International Semiconductor Ltd.Inventors: Tejasvi Das, John L. Melanson