Patents by Inventor Fred F. Chen
Fred F. Chen 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: 11706061Abstract: A high-speed signaling system with adaptive transmit pre-emphasis. A transmit circuit has a plurality of output drivers to output a first signal onto a signal path. A receive circuit is coupled to receive the first signal via the signal path and configured to generate an indication of whether the first signal exceeds a threshold level. A first threshold control circuit is coupled to receive the indication from the receive circuit and configured to adjust the threshold level according to whether the first signal exceeds the threshold level. A drive strength control circuit is coupled to receive the indication from the receive circuit and configured to adjust a drive strength of at least one output driver of the plurality of output drivers according to whether the first signal exceeds the threshold level.Type: GrantFiled: January 11, 2022Date of Patent: July 18, 2023Assignee: Rambus Inc.Inventors: Vladimir M. Stojanovic, Andrew C. Ho, Anthony Bessios, Fred F. Chen, Elad Alon, Mark A. Horowitz
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Publication number: 20220209999Abstract: A high-speed signaling system with adaptive transmit pre-emphasis. A transmit circuit has a plurality of output drivers to output a first signal onto a signal path. A receive circuit is coupled to receive the first signal via the signal path and configured to generate an indication of whether the first signal exceeds a threshold level. A first threshold control circuit is coupled to receive the indication from the receive circuit and configured to adjust the threshold level according to whether the first signal exceeds the threshold level. A drive strength control circuit is coupled to receive the indication from the receive circuit and configured to adjust a drive strength of at least one output driver of the plurality of output drivers according to whether the first signal exceeds the threshold level.Type: ApplicationFiled: January 11, 2022Publication date: June 30, 2022Inventors: Vladimir M. Stojanovic, Andrew C. Ho, Anthony Bessios, Fred F. Chen, Elad Alon, Mark A. Horowitz
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Publication number: 20220182158Abstract: Described are methods and circuits for margin testing digital receivers. These methods and circuits prevent margins from collapsing in response to erroneously received data and can thus be used in receivers that employ historical data to reduce intersymbol interference (ISI). Some embodiments detect receive errors for input data streams of unknown patterns and can thus be used for in-system margin testing. Such systems can be adapted to dynamically alter system parameters during device operation to maintain adequate margins despite fluctuations in the system noise environment due to e.g. temperature and supply-voltage changes. Also described are methods of plotting and interpreting filtered and unfiltered error data generated by the disclosed methods and circuits. Some embodiments filter error data to facilitate pattern-specific margin testing.Type: ApplicationFiled: December 21, 2021Publication date: June 9, 2022Inventors: Andrew Ho, Vladimir Stojanovic, Bruno W. Garlepp, Fred F. Chen
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Publication number: 20220103405Abstract: A signaling system includes a pre-emphasizing transmitter and an equalizing receiver coupled to one another via a high-speed signal path. The receiver measures the quality of data conveyed from the transmitter. A controller uses this information and other information to adaptively establish appropriate transmit pre-emphasis and receive equalization settings, e.g. to select the lowest power setting for which the signaling system provides some minimum communication bandwidth without exceeding a desired bit-error rate.Type: ApplicationFiled: October 15, 2021Publication date: March 31, 2022Inventors: Jared L. Zerbe, Fred F. Chen, Andrew Ho, Ramin Farjad-Rad, John W. Poulton, Kevin S. Donnelly, Brian S. Leibowitz, Vladimir Stojanovic
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Patent number: 11290305Abstract: A signaling circuit having a selectable-tap equalizer. The signaling circuit includes a buffer, a select circuit and an equalizing circuit. The buffer is used to store a plurality of data values that correspond to data signals transmitted on a signaling path during a first time interval. The select circuit is coupled to the buffer to select a subset of data values from the plurality of data values according to a select value. The equalizing circuit is coupled to receive the subset of data values from the select circuit and is adapted to adjust, according to the subset of data values, a signal level that corresponds to a data signal transmitted on the signaling path during a second time interval.Type: GrantFiled: September 18, 2020Date of Patent: March 29, 2022Assignee: Highlands, LLCInventors: Jared L. Zerbe, Vladimir M. Stojanovic, Fred F. Chen
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Patent number: 11233678Abstract: A high-speed signaling system with adaptive transmit pre-emphasis. A transmit circuit has a plurality of output drivers to output a first signal onto a signal path. A receive circuit is coupled to receive the first signal via the signal path and configured to generate an indication of whether the first signal exceeds a threshold level. A first threshold control circuit is coupled to receive the indication from the receive circuit and configured to adjust the threshold level according to whether the first signal exceeds the threshold level. A drive strength control circuit is coupled to receive the indication from the receive circuit and configured to adjust a drive strength of at least one output driver of the plurality of output drivers according to whether the first signal exceeds the threshold level.Type: GrantFiled: August 21, 2020Date of Patent: January 25, 2022Assignee: Rambus Inc.Inventors: Vladimir M. Stojanovic, Andrew C. Ho, Anthony Bessios, Fred F. Chen, Elad Alon, Mark A. Horowitz
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Patent number: 11233589Abstract: Described are methods and circuits for margin testing digital receivers. These methods and circuits prevent margins from collapsing in response to erroneously received data and can thus be used in receivers that employ historical data to reduce intersymbol interference (ISI). Some embodiments detect receive errors for input data streams of unknown patterns and can thus be used for in-system margin testing. Such systems can be adapted to dynamically alter system parameters during device operation to maintain adequate margins despite fluctuations in the system noise environment due to e.g. temperature and supply-voltage changes. Also described are methods of plotting and interpreting filtered and unfiltered error data generated by the disclosed methods and circuits. Some embodiments filter error data to facilitate pattern-specific margin testing.Type: GrantFiled: November 24, 2020Date of Patent: January 25, 2022Assignee: Rambus Inc.Inventors: Andrew Ho, Vladimir Stojanovic, Bruno W. Garlepp, Fred F. Chen
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Patent number: 11165613Abstract: A signaling system includes a pre-emphasizing transmitter and an equalizing receiver coupled to one another via a high-speed signal path. The receiver measures the quality of data conveyed from the transmitter. A controller uses this information and other information to adaptively establish appropriate transmit pre-emphasis and receive equalization settings, e.g. to select the lowest power setting for which the signaling system provides some minimum communication bandwidth without exceeding a desired bit-error rate.Type: GrantFiled: January 24, 2019Date of Patent: November 2, 2021Assignee: Rambus Inc.Inventors: Jared L. Zerbe, Fred F. Chen, Andrew Ho, Ramin Farjad-Rad, John W. Poulton, Kevin S. Donnelly, Brian S. Leibowitz, Vladimir Stojanovic
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Publication number: 20210126722Abstract: Described are methods and circuits for margin testing digital receivers. These methods and circuits prevent margins from collapsing in response to erroneously received data and can thus be used in receivers that employ historical data to reduce intersymbol interference (ISI). Some embodiments detect receive errors for input data streams of unknown patterns and can thus be used for in-system margin testing. Such systems can be adapted to dynamically alter system parameters during device operation to maintain adequate margins despite fluctuations in the system noise environment due to e.g. temperature and supply-voltage changes. Also described are methods of plotting and interpreting filtered and unfiltered error data generated by the disclosed methods and circuits. Some embodiments filter error data to facilitate pattern-specific margin testing.Type: ApplicationFiled: November 24, 2020Publication date: April 29, 2021Inventors: Andrew Ho, Vladimir Stojanovic, Bruno W. Garlepp, Fred F. Chen
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Publication number: 20210067384Abstract: A signaling circuit having a selectable-tap equalizer. The signaling circuit includes a buffer, a select circuit and an equalizing circuit. The buffer is used to store a plurality of data values that correspond to data signals transmitted on a signaling path during a first time interval. The select circuit is coupled to the buffer to select a subset of data values from the plurality of data values according to a select value. The equalizing circuit is coupled to receive the subset of data values from the select circuit and is adapted to adjust, according to the subset of data values, a signal level that corresponds to a data signal transmitted on the signaling path during a second time interval.Type: ApplicationFiled: September 18, 2020Publication date: March 4, 2021Inventors: Jared L. Zerbe, Vladimir M. Stojanovic, Fred F. Chen
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Publication number: 20210051047Abstract: A high-speed signaling system with adaptive transmit pre-emphasis. A transmit circuit has a plurality of output drivers to output a first signal onto a signal path. A receive circuit is coupled to receive the first signal via the signal path and configured to generate an indication of whether the first signal exceeds a threshold level. A first threshold control circuit is coupled to receive the indication from the receive circuit and configured to adjust the threshold level according to whether the first signal exceeds the threshold level. A drive strength control circuit is coupled to receive the indication from the receive circuit and configured to adjust a drive strength of at least one output driver of the plurality of output drivers according to whether the first signal exceeds the threshold level.Type: ApplicationFiled: August 21, 2020Publication date: February 18, 2021Inventors: Vladimir M. Stojanovic, Andrew C. Ho, Anthony Bessios, Fred F. Chen, Elad Alon, Mark A. Horowitz
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Publication number: 20210006341Abstract: Described are methods and circuits for margin testing digital receivers. These methods and circuits prevent margins from collapsing in response to erroneously received data and can thus be used in receivers that employ historical data to reduce intersymbol interference (ISI). Some embodiments detect receive errors for input data streams of unknown patterns and can thus be used for in-system margin testing. Such systems can be adapted to dynamically alter system parameters during device operation to maintain adequate margins despite fluctuations in the system noise environment due to e.g. temperature and supply-voltage changes. Also described are methods of plotting and interpreting filtered and unfiltered error data generated by the disclosed methods and circuits. Some embodiments filter error data to facilitate pattern-specific margin testing.Type: ApplicationFiled: July 16, 2020Publication date: January 7, 2021Inventors: Andrew Ho, Vladimir Stojanovic, Bruno W. Garlepp, Fred F. Chen
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Patent number: 10880022Abstract: Described are methods and circuits for margin testing digital receivers. These methods and circuits prevent margins from collapsing in response to erroneously received data and can thus be used in receivers that employ historical data to reduce intersymbol interference (ISI). Some embodiments detect receive errors for input data streams of unknown patterns and can thus be used for in-system margin testing. Such systems can be adapted to dynamically alter system parameters during device operation to maintain adequate margins despite fluctuations in the system noise environment due to e.g. temperature and supply-voltage changes. Also described are methods of plotting and interpreting filtered and unfiltered error data generated by the disclosed methods and circuits. Some embodiments filter error data to facilitate pattern-specific margin testing.Type: GrantFiled: July 16, 2020Date of Patent: December 29, 2020Assignee: Rambus Inc.Inventors: Andrew Ho, Vladimir Stojanovic, Bruno W. Garlepp, Fred F. Chen
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Patent number: 10812297Abstract: A signaling circuit having a selectable-tap equalizer. The signaling circuit includes a buffer, a select circuit and an equalizing circuit. The buffer is used to store a plurality of data values that correspond to data signals transmitted on a signaling path during a first time interval. The select circuit is coupled to the buffer to select a subset of data values from the plurality of data values according to a select value. The equalizing circuit is coupled to receive the subset of data values from the select circuit and is adapted to adjust, according to the subset of data values, a signal level that corresponds to a data signal transmitted on the signaling path during a second time interval.Type: GrantFiled: April 6, 2020Date of Patent: October 20, 2020Assignee: Rambus Inc.Inventors: Jared L. Zerbe, Vladimir M. Stojanovic, Fred F. Chen
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Publication number: 20200304348Abstract: A signaling circuit having a selectable-tap equalizer. The signaling circuit includes a buffer, a select circuit and an equalizing circuit. The buffer is used to store a plurality of data values that correspond to data signals transmitted on a signaling path during a first time interval. The select circuit is coupled to the buffer to select a subset of data values from the plurality of data values according to a select value. The equalizing circuit is coupled to receive the subset of data values from the select circuit and is adapted to adjust, according to the subset of data values, a signal level that corresponds to a data signal transmitted on the signaling path during a second time interval.Type: ApplicationFiled: April 6, 2020Publication date: September 24, 2020Inventors: Jared L. Zerbe, Vladimir M. Stojanovic, Fred F. Chen
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Patent number: 10771295Abstract: A high-speed signaling system with adaptive transmit pre-emphasis. A transmit circuit has a plurality of output drivers to output a first signal onto a signal path. A receive circuit is coupled to receive the first signal via the signal path and configured to generate an indication of whether the first signal exceeds a threshold level. A first threshold control circuit is coupled to receive the indication from the receive circuit and configured to adjust the threshold level according to whether the first signal exceeds the threshold level. A drive strength control circuit is coupled to receive the indication from the receive circuit and configured to adjust a drive strength of at least one output driver of the plurality of output drivers according to whether the first signal exceeds the threshold level.Type: GrantFiled: August 22, 2019Date of Patent: September 8, 2020Assignee: Rambus Inc.Inventors: Vladimir M. Stojanovic, Andrew C. Ho, Anthony Bessios, Fred F. Chen, Elad Alon, Mark A. Horowitz
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Patent number: 10735116Abstract: Described are methods and circuits for margin testing digital receivers. These methods and circuits prevent margins from collapsing in response to erroneously received data and can thus be used in receivers that employ historical data to reduce intersymbol interference (ISI). Some embodiments detect receive errors for input data streams of unknown patterns and can thus be used for in-system margin testing. Such systems can be adapted to dynamically alter system parameters during device operation to maintain adequate margins despite fluctuations in the system noise environment due to e.g. temperature and supply-voltage changes. Also described are methods of plotting and interpreting filtered and unfiltered error data generated by the disclosed methods and circuits. Some embodiments filter error data to facilitate pattern-specific margin testing.Type: GrantFiled: December 20, 2018Date of Patent: August 4, 2020Assignee: Rambus Inc.Inventors: Andrew Ho, Vladimir Stojanovic, Bruno W. Garlepp, Fred F. Chen
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Patent number: 10652052Abstract: A signaling circuit having a selectable-tap equalizer. The signaling circuit includes a buffer, a select circuit and an equalizing circuit. The buffer is used to store a plurality of data values that correspond to data signals transmitted on a signaling path during a first time interval. The select circuit is coupled to the buffer to select a subset of data values from the plurality of data values according to a select value. The equalizing circuit is coupled to receive the subset of data values from the select circuit and is adapted to adjust, according to the subset of data values, a signal level that corresponds to a data signal transmitted on the signaling path during a second time interval.Type: GrantFiled: June 5, 2019Date of Patent: May 12, 2020Assignee: Rambus Inc.Inventors: Jared L. Zerbe, Vladimir M. Stojanovic, Fred F. Chen
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Publication number: 20200084073Abstract: A high-speed signaling system with adaptive transmit pre-emphasis. A transmit circuit has a plurality of output drivers to output a first signal onto a signal path. A receive circuit is coupled to receive the first signal via the signal path and configured to generate an indication of whether the first signal exceeds a threshold level. A first threshold control circuit is coupled to receive the indication from the receive circuit and configured to adjust the threshold level according to whether the first signal exceeds the threshold level. A drive strength control circuit is coupled to receive the indication from the receive circuit and configured to adjust a drive strength of at least one output driver of the plurality of output drivers according to whether the first signal exceeds the threshold level.Type: ApplicationFiled: August 22, 2019Publication date: March 12, 2020Inventors: Vladimir M. Stojanovic, Andrew C. Ho, Anthony Bessios, Fred F. Chen, Elad Alon, Mark A. Horowitz
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Publication number: 20190342127Abstract: A signaling circuit having a selectable-tap equalizer. The signaling circuit includes a buffer, a select circuit and an equalizing circuit. The buffer is used to store a plurality of data values that correspond to data signals transmitted on a signaling path during a first time interval. The select circuit is coupled to the buffer to select a subset of data values from the plurality of data values according to a select value. The equalizing circuit is coupled to receive the subset of data values from the select circuit and is adapted to adjust, according to the subset of data values, a signal level that corresponds to a data signal transmitted on the signaling path during a second time interval.Type: ApplicationFiled: June 5, 2019Publication date: November 7, 2019Inventors: Jared L. Zerbe, Vladimir M. Stojanovic, Fred F. Chen