Patents by Inventor Yingxuan Li

Yingxuan Li 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).

  • Patent number: 6809600
    Abstract: Dual loop phase lock loops having a high loop bandwidth with low power consumption are described. Each loop is provided with a voltage supply regulator circuit which regulates the voltage of a portion of each loop. In one embodiment, the outer loop employs a regulation circuit comprising a two stage operational amplifier which is compensated by a compensation circuit that is configured to ensure that the dominant pole of the operational amplifier is associated with the first stage of the operational amplifier.
    Type: Grant
    Filed: January 3, 2003
    Date of Patent: October 26, 2004
    Assignee: Rambus Inc.
    Inventors: Kun-Yung Ken Chang, Yingxuan Li, Stefanos Sidiropoulos
  • Patent number: 6674377
    Abstract: A circuit, apparatus and method for efficiently and accurately calibrating an output driver current are provided in embodiments of the present invention. In an embodiment of the present invention, a circuit comprises a first digital-to-analog converter (“DAC”) that generates a first current. A first transistor is coupled to the first DAC and generates a first biasing current responsive to the first current. A second DAC is coupled to the first transistor and generates a first control current responsive to the first biasing current. According to an embodiment of the present invention, the first and second DACs are binary weighted control DACs. According to an embodiment of the present invention, the binary weighted values of the second DAC are obtained in response to a calibration signal generated by a controller. According to an embodiment of the present invention, the first DAC is an M-bit DAC and the second DAC is an N-bit DAC, wherein M is less than N.
    Type: Grant
    Filed: April 25, 2002
    Date of Patent: January 6, 2004
    Assignee: Rambus Inc.
    Inventor: Yingxuan Li
  • Patent number: 6618786
    Abstract: A current-mode bus line driver includes a primary current source and a supplemental current source. The primary current source is an open-drain NMOS transistor, whose output current decreases at low output voltages. The supplemental current source is responsive to low output voltages to provide a supplemental output current, in addition to the output current of the primary current source. The supplemental current source consists of an inverter and a current mirror. The inverter produces a correction current that is inversely related to the voltage output of the primary current source. This correction current is amplified by the current mirror to produce the supplemental output current. The current mirror is self-limiting, in that its current output falls off at very low output voltages.
    Type: Grant
    Filed: August 28, 2000
    Date of Patent: September 9, 2003
    Assignee: Rambus Inc.
    Inventors: Stefanos Sidiropoulos, Yingxuan Li
  • Publication number: 20030122621
    Abstract: A reconfigurable dual-mode multiple stage operational amplifier circuit includes a configurable portion that can be selectively configured to operate in either a one-pole mode or a two-pole mode. Different exemplary operational amplifier circuits are provided, some of which employ a compensation portion that can be selectively coupled to the configurable portion. For example, in the one-pole operating mode the compensation portion is decoupled from an output of the configurable portion. Conversely, in the two-pole operating mode the compensation portion is coupled to the output. The compensation portion is configured to stabilize a signal on the output. The configurable portion switches between operational modes in response to at least one control signal. The operational amplifier may include a pulse generating portion that is coupled to operatively control the configurable portion in response to the at least one control signal. Such an implementation negates the need for a compensation portion.
    Type: Application
    Filed: February 18, 2003
    Publication date: July 3, 2003
    Inventors: Stefanos Sidiropoulos, Yingxuan Li
  • Publication number: 20030107418
    Abstract: Dual loop phase lock loops having a high loop bandwidth with low power consumption are described. Each loop is provided with a voltage supply regulator circuit which regulates the voltage of a portion of each loop. In one embodiment, the outer loop employs a regulation circuit comprising a two stage operational amplifier which is compensated by a compensation circuit that is configured to ensure that the dominant pole of the operational amplifier is associated with the first stage of the operational amplifier.
    Type: Application
    Filed: January 3, 2003
    Publication date: June 12, 2003
    Inventors: Kun-Yung Ken Chang, Yingxuan Li, Stefanos Sidiropoulos
  • Patent number: 6573779
    Abstract: Disclosed herein is a process-tracking clock duty cycle integrator. Common mode feedback is used to set a common mode output voltage that varies with the voltage threshold of MOS elements that implement the circuit. In addition, a buffer is used to control the common mode input voltage to the differential amplifier circuit, and to vary the common mode input voltage with the voltage threshold.
    Type: Grant
    Filed: May 25, 2001
    Date of Patent: June 3, 2003
    Assignee: Rambus Inc.
    Inventors: Stefanos Sidiropoulos, Yingxuan Li
  • Patent number: 6522199
    Abstract: A reconfigurable dual-mode multiple stage operational amplifier circuit includes a configurable portion that can be selectively configured to operate in either a one-pole mode or a two-pole mode. Different exemplary operational amplifier circuits are provided, some of which employ a compensation portion that can be selectively coupled to the configurable portion. For example, in the one-pole operating mode the compensation portion is decoupled from an output of the configurable portion. Conversely, in the two-pole operating mode the compensation portion is coupled to the output. The compensation portion is configured to stabilize a signal on the output. The configurable portion switches between operational modes in response to at least one control signal. The operational amplifier may include a pulse generating portion that is coupled to operatively control the configurable portion in response to the at least one control signal. Such an implementation negates the need for a compensation portion.
    Type: Grant
    Filed: May 18, 2001
    Date of Patent: February 18, 2003
    Assignee: Rambus, Inc.
    Inventors: Stefanos Sidiropoulos, Yingxuan Li
  • Patent number: 6504438
    Abstract: Dual loop phase lock loops having a high loop bandwidth with low power consumption are described. Each loop is provided with a voltage supply regulator circuit which regulates the voltage of a portion of each loop. In one embodiment, the outer loop employs a regulation circuit comprising a two stage operational amplifier which is compensated by a compensation circuit that is configured to ensure that the dominant pole of the operational amplifier is associated with the first stage of the operational amplifier.
    Type: Grant
    Filed: September 17, 2001
    Date of Patent: January 7, 2003
    Assignee: Rambus, Inc.
    Inventors: Kun-Yung Ken Chang, Yingxuan Li, Stefanos Sidiropoulos
  • Publication number: 20020175739
    Abstract: Disclosed herein is a process-tracking clock duty cycle integrator. Common mode feedback is used to set a common mode output voltage that varies with the voltage threshold of MOS elements that implement the circuit. In addition, a buffer is used to control the common mode input voltage to the differential amplifier circuit, and to vary the common mode input voltage with the voltage threshold.
    Type: Application
    Filed: May 25, 2001
    Publication date: November 28, 2002
    Inventors: Stefanos Sidiropoulos, Yingxuan Li
  • Publication number: 20020171487
    Abstract: A reconfigurable dual-mode multiple stage operational amplifier circuit includes a configurable portion that can be selectively configured to operate in either a one-pole mode or a two-pole mode. Different exemplary operational amplifier circuits are provided, some of which employ a compensation portion that can be selectively coupled to the configurable portion. For example, in the one-pole operating mode the compensation portion is decoupled from an output of the configurable portion. Conversely, in the two-pole operating mode the compensation portion is coupled to the output. The compensation portion is configured to stabilize a signal on the output. The configurable portion switches between operational modes in response to at least one control signal. The operational amplifier may include a pulse generating portion that is coupled to operatively control the configurable portion in response to the at least one control signal. Such an implementation negates the need for a compensation portion.
    Type: Application
    Filed: May 18, 2001
    Publication date: November 21, 2002
    Inventors: Stefanos Sidiropoulos, Yingxuan Li