Patents by Inventor Chris C. Dao

Chris C. Dao 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).

  • Publication number: 20140266098
    Abstract: A voltage regulator includes an amplifier having a first input coupled to a first reference voltage and a second input coupled to a voltage feedback signal; a multiplexer having a first input coupled to an output of the amplifier, a second input coupled to a voltage clamp signal, and a control input; and a control circuit having a first input coupled to an over current indicator, a second input coupled to a no over voltage indicator, a third input coupled to a timer signal, and an output coupled to the control input of the multiplexer.
    Type: Application
    Filed: March 14, 2013
    Publication date: September 18, 2014
    Inventors: Chris C. Dao, Stefano Pietri, Juxiang Ren
  • Publication number: 20140203794
    Abstract: A bandgap reference system has a bandgap circuit, an operational transconductance amplifier, and an offset controller. The bandgap circuit includes a pair of diode devices and has a reference terminal at which is provided a bandgap reference voltage. The bandgap circuit provides a differential output having a first output and a second output. The operational transconductance amplifier has a first input coupled to the first output of the bandgap circuit, a second input coupled to the second output of the bandgap reference circuit, and an output coupled to the reference terminal. The offset controller is coupled to the operational transconductance amplifier and to the first and second outputs of the bandgap circuit. The offset controller trims the operational transconductance amplifier as needed to ensure an offset of the operational transconductance amplifier is below a predetermined level.
    Type: Application
    Filed: January 24, 2013
    Publication date: July 24, 2014
    Inventors: STEFANO PIETRI, Chris C. Dao, Juxiang Ren
  • Publication number: 20140118036
    Abstract: A voltage regulator bypass circuit to control bypass of a voltage regulator of an integrated circuit device, the voltage regulator bypass circuit including a first voltage detector, a second voltage detector, and circuit. The first voltage detector to detect that a core circuitry voltage level is above a first threshold and to assert a first detect signal at an output in response to the detection. The second voltage detector to detect that an unregulated supply voltage is above a second threshold and to assert a second detect signal at an output in response to the detection. The circuit having a first input coupled to the output of the first voltage detector and a second input coupled to the output of the second voltage detector, the circuit to bypass the voltage regulator in response the output of the latch being cleared.
    Type: Application
    Filed: December 13, 2013
    Publication date: May 1, 2014
    Applicants: FREESCALE SEMICONDUCTOR, INC., STMICROELECTRONICS PRIVATE LTD., STMICROELECTRONICS SRL
    Inventors: Stefano Pietri, Chris C. Dao, Juxiang Ren, Nicolas Grossier, V. Srinivasan
  • Patent number: 8629713
    Abstract: A voltage regulator bypass circuit to control bypass of a voltage regulator of an integrated circuit device, the voltage regulator bypass circuit including a first voltage detector, a second voltage detector, and circuit. The first voltage detector to detect that a core circuitry voltage level is above a first threshold and to assert a first detect signal at an output in response to the detection. The second voltage detector to detect that an unregulated supply voltage is above a second threshold and to assert a second detect signal at an output in response to the detection. The circuit having a first input coupled to the output of the first voltage detector and a second input coupled to the output of the second voltage detector, the circuit to bypass the voltage regulator in response the output of the latch being cleared.
    Type: Grant
    Filed: May 29, 2012
    Date of Patent: January 14, 2014
    Assignees: Freescale Semiconductor, Inc., STMicroelectronics SRL, STMicroelectronics Private Ltd.
    Inventors: Stefano Pietri, Chris C. Dao, Juxiang Ren, Nicolas Grosssier, V Srinivasan
  • Publication number: 20130321071
    Abstract: A voltage regulator bypass circuit to control bypass of a voltage regulator of an integrated circuit device, the voltage regulator bypass circuit including a first voltage detector, a second voltage detector, and circuit. The first voltage detector to detect that a core circuitry voltage level is above a first threshold and to assert a first detect signal at an output in response to the detection. The second voltage detector to detect that an unregulated supply voltage is above a second threshold and to assert a second detect signal at an output in response to the detection. The circuit having a first input coupled to the output of the first voltage detector and a second input coupled to the output of the second voltage detector, the circuit to bypass the voltage regulator in response the output of the latch being cleared.
    Type: Application
    Filed: May 29, 2012
    Publication date: December 5, 2013
    Applicants: FREESCALE SEMICONDUCTOR, INC., STMICROELECTRONICS PRIVATE LTD., STMICROELECTRONICS SRL
    Inventors: Stefano Pietri, Chris C. Dao, Juxiang Ren, Nicolas Grossier, V. Srinivasan
  • Patent number: 8552700
    Abstract: A voltage regulator includes a transistor, a comparator, and a compensation circuit. The comparator has a first input terminal coupled to receive a clock signal, a second input terminal, and an output terminal coupled to a control electrode of the transistor. The compensation circuit has a first input terminal coupled to receive a reference voltage, a second input terminal coupled to the output terminal of the voltage regulator, and an output terminal coupled to the second input terminal of the comparator. The compensation circuit has a filter circuit. The filter circuit has a first RC time constant during startup of the voltage regulator, and the filter circuit has a second RC time constant during normal operation. Changing the RC time constant for startup prevents an overshoot of an output voltage of the voltage regulator.
    Type: Grant
    Filed: October 6, 2010
    Date of Patent: October 8, 2013
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Chris C. Dao, Stefano Pietri, Juxiang Ren
  • Publication number: 20130234743
    Abstract: An integrated circuit facilitates a self test routine that verifies proper operation of an analog comparator. In response to entering the self test routine, the voltage provided to an input of a comparator is changed from being at an operating voltage supply to being at a self test voltage that is used to verify operation of the comparator. In response to the comparator operating properly, the self test voltage provided to the input of the comparator is replaced with the operating voltage supply, and normal operation resumes. The duration of the self test cycle is based upon the amount of time during which the self test voltage is provided to the comparator is asynchronous in nature, and therefore not a function of a clock signal.
    Type: Application
    Filed: March 7, 2012
    Publication date: September 12, 2013
    Applicant: FREESCALE SEMICONDUCTOR, INC.
    Inventors: Juxiang Ren, Chris C. Dao, Stefano Pietri
  • Patent number: 8456784
    Abstract: An overvoltage protection circuit may include a reference voltage generator, a trigger circuit, and a clamping device. The reference voltage generator is for providing a reference voltage that is relatively constant during a powered EOS/ESD event. The trigger circuit is coupled to receive the reference voltage and a power supply voltage. The trigger circuit is for comparing the reference voltage to the power supply voltage. In response to detecting that the power supply voltage is above the reference voltage, the trigger circuit provides a trigger signal having a voltage proportional to a voltage level of the overvoltage event. The clamping device is coupled between a first power supply terminal and a second power supply terminal. The clamping device is for providing a current path between the first and second power supply terminals in response to the trigger signal.
    Type: Grant
    Filed: May 3, 2010
    Date of Patent: June 4, 2013
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Michael A. Stockinger, Chris C. Dao, Dale J. McQuirk
  • Publication number: 20130113449
    Abstract: A test method and system are provided for testing a switched mode power supply in open loop on an automated test equipment device by applying a low frequency waveform signal (209) to a compensator filter (225) and simultaneously capturing and processing the input (223) and output (222) to the compensator filter (225) to determine the phase difference therebetween.
    Type: Application
    Filed: November 4, 2011
    Publication date: May 9, 2013
    Inventors: Stefano Pietri, Chris C. Dao, Garrin S. Felber
  • Patent number: 8362814
    Abstract: A data processing system includes a brown-out detection circuit with a first resistive element, a first transistor, a second transistor, and a comparator. The first resistive element has a first terminal coupled to a first power supply voltage terminal, and a second terminal. The first transistor has a first current electrode coupled to the second terminal of the first resistive element, a control electrode, and a second current electrode. The second transistor has a first current electrode coupled to the second current electrode of the first transistor, a control electrode, and a second current electrode coupled to a second power supply voltage terminal. The comparator has a first input terminal coupled to the first terminal of the first resistive element, a second input terminal coupled to the second terminal of the first resistive element, and an output terminal for providing a brown-out detection signal.
    Type: Grant
    Filed: July 19, 2012
    Date of Patent: January 29, 2013
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Chris C. Dao, Stefano Pietri, Andre Luis Vilas Boas
  • Publication number: 20120281491
    Abstract: A data processing system includes a brown-out detection circuit with a first resistive element, a first transistor, a second transistor, and a comparator. The first resistive element has a first terminal coupled to a first power supply voltage terminal, and a second terminal. The first transistor has a first current electrode coupled to the second terminal of the first resistive element, a control electrode, and a second current electrode. The second transistor has a first current electrode coupled to the second current electrode of the first transistor, a control electrode, and a second current electrode coupled to a second power supply voltage terminal. The comparator has a first input terminal coupled to the first terminal of the first resistive element, a second input terminal coupled to the second terminal of the first resistive element, and an output terminal for providing a brown-out detection signal.
    Type: Application
    Filed: July 19, 2012
    Publication date: November 8, 2012
    Applicant: FREESCALE SEMICONDUCTOR, INC.
    Inventors: Chris C. Dao, Stefano Pietri, Andre Luis Vilas Boas
  • Patent number: 8253453
    Abstract: A data processing system (100), such as a System-on-Chip, includes a processor (120), a memory (140) that has an expected minimum data retention voltage, and a brown-out detector (160), which includes a brown-out detection circuit (201) that has an analog output, and an output circuit (248 and 252) that converts the analog output of the brown-out detection circuit to a digital brown-out flag. The brown-out detection circuit includes a self-biased current reference, current mirrors, and a current comparator. The brown-out detector monitors voltage of a power supply of the memory, and the brown-out detector asserts the digital brown-out flag to the processor when the voltage of the power supply is at, or slightly above, a highest expected minimum data retention voltage.
    Type: Grant
    Filed: October 28, 2010
    Date of Patent: August 28, 2012
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Andre Luis Vilas Boas, Chris C. Dao, Stefano Pietri
  • Patent number: 8228100
    Abstract: A brown-out detection circuit includes a first resistive element, a first transistor, a second transistor, and a comparator. The first resistive element has a first terminal coupled to a first power supply voltage terminal, and a second terminal. The first transistor is of a first conductivity type and has a first current electrode coupled to the second terminal of the first resistive element, a control electrode, and a second current electrode. The second transistor is of a second conductivity type and has a first current electrode coupled to the second current electrode of the first transistor, a control electrode, and a second current electrode coupled to a second power supply voltage terminal. The comparator has a first input terminal coupled to the first terminal of the first resistive element, a second input terminal coupled to the second terminal of the first resistive element, and an output terminal for providing a brown-out detection signal.
    Type: Grant
    Filed: January 26, 2010
    Date of Patent: July 24, 2012
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Chris C. Dao, Stefano Pietri, Andre Luis Vilas Boas
  • Publication number: 20120105108
    Abstract: A data processing system (100), such as a System-on-Chip, includes a processor (120), a memory (140) that has an expected minimum data retention voltage, and a brown-out detector (160), which includes a brown-out detection circuit (201) that has an analog output, and an output circuit (248 and 252) that converts the analog output of the brown-out detection circuit to a digital brown-out flag. The brown-out detection circuit includes a self-biased current reference, current mirrors, and a current comparator. The brown-out detector monitors voltage of a power supply of the memory, and the brown-out detector asserts the digital brown-out flag to the processor when the voltage of the power supply is at, or slightly above, a highest expected minimum data retention voltage.
    Type: Application
    Filed: October 28, 2010
    Publication date: May 3, 2012
    Applicant: Freescale Semiconductor, Inc.
    Inventors: Andre Luis Vilas Boas, Chris C. Dao, Stefano Pietri
  • Publication number: 20120086423
    Abstract: A voltage regulator includes a transistor, a comparator, and a compensation circuit. The comparator has a first input terminal coupled to receive a clock signal, a second input terminal, and an output terminal coupled to a control electrode of the transistor. The compensation circuit has a first input terminal coupled to receive a reference voltage, a second input terminal coupled to the output terminal of the voltage regulator, and an output terminal coupled to the second input terminal of the comparator. The compensation circuit has a filter circuit. The filter circuit has a first RC time constant during startup of the voltage regulator, and the filter circuit has a second RC time constant during normal operation. Changing the RC time constant for startup prevents an overshoot of an output voltage of the voltage regulator.
    Type: Application
    Filed: October 6, 2010
    Publication date: April 12, 2012
    Inventors: Chris C. Dao, Stefano Pietri, Juxiang Ren
  • Publication number: 20110267723
    Abstract: An overvoltage protection circuit may include a reference voltage generator, a trigger circuit, and a clamping device. The reference voltage generator is for providing a reference voltage that is relatively constant during a powered EOS/ESD event. The trigger circuit is coupled to receive the reference voltage and a power supply voltage. The trigger circuit is for comparing the reference voltage to the power supply voltage. In response to detecting that the power supply voltage is above the reference voltage, the trigger circuit provides a trigger signal having a voltage proportional to a voltage level of the overvoltage event. The clamping device is coupled between a first power supply terminal and a second power supply terminal. The clamping device is for providing a current path between the first and second power supply terminals in response to the trigger signal.
    Type: Application
    Filed: May 3, 2010
    Publication date: November 3, 2011
    Inventors: Michael A. Stockinger, Chris C. Dao, Dale J. McQuirk
  • Publication number: 20110185212
    Abstract: A brown-out detection circuit comprises a first resistive element, a first transistor, a second transistor, and a comparator. The first resistive element has a first terminal coupled to a first power supply voltage terminal, and a second terminal. The first transistor is of a first conductivity type and has a first current electrode coupled to the second terminal of the first resistive element, a control electrode, and a second current electrode. The second transistor is of a second conductivity type and has a first current electrode coupled to the second current electrode of the first transistor, a control electrode, and a second current electrode coupled to a second power supply voltage terminal. The comparator has a first input terminal coupled to the first terminal of the first resistive element, a second input terminal coupled to the second terminal of the first resistive element, and an output terminal for providing a brown-out detection signal.
    Type: Application
    Filed: January 26, 2010
    Publication date: July 28, 2011
    Inventors: CHRIS C. DAO, Stefano Pietri, Andre Luis Vilas Boas
  • Patent number: 7924108
    Abstract: An oscillator circuit has a crystal oscillator amplifier having only two clock input terminals, one being an input terminal and the other being an output terminal. The input terminal allows a user of the integrated circuit to choose between connecting a first clock signal generated from a crystal or a second clock signal generated by a non-crystal source to the input terminal. Control circuitry has a capacitor coupled in parallel with a transistor. Both are coupled in series with a resistive device at an output of the control circuitry to provide a control signal. Clock generation circuitry coupled to the crystal oscillator amplifier provides an oscillating output signal in response to an enable signal. In one form a comparator circuit provides the oscillating output signal. The control signal is used to ensure that inputs to the comparator circuit repeatedly cross each other over time.
    Type: Grant
    Filed: August 14, 2009
    Date of Patent: April 12, 2011
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Chris C. Dao, Stefano Pietri, Wenzhong Zhang
  • Publication number: 20110037524
    Abstract: An oscillator circuit has a crystal oscillator amplifier having only two clock input terminals, one being an input terminal and the other being an output terminal. The input terminal allows a user of the integrated circuit to choose between connecting a first clock signal generated from a crystal or a second clock signal generated by a non-crystal source to the input terminal. Control circuitry has a capacitor coupled in parallel with a transistor. Both are coupled in series with a resistive device at an output of the control circuitry to provide a control signal. Clock generation circuitry coupled to the crystal oscillator amplifier provides an oscillating output signal in response to an enable signal. In one form a comparator circuit provides the oscillating output signal. The control signal is used to ensure that inputs to the comparator circuit repeatedly cross each other over time.
    Type: Application
    Filed: August 14, 2009
    Publication date: February 17, 2011
    Inventors: Chris C. Dao, Stefano Pietri, Wenzhong Zhang
  • Patent number: 7834689
    Abstract: An amplifier has an input stage coupled to a current mirror for providing a first control signal. A gain boosting stage has first and second sections, each having first and second inputs and an output. The first input of the first section is coupled to the input stage. The second input of the first section is a first node between a source and a drain of a first pair of series-coupled transistors. The first input of the second section is coupled to the current mirror. The second input of the second section is a second node between a source and a drain of a second pair of series-coupled transistors. A pre-driver stage has inputs coupled to the input stage and the gain boosting stage. The pre-driver stage provides inputs to the gain boosting stage and receives outputs from the gain boosting stage prior to coupling to an output stage.
    Type: Grant
    Filed: July 22, 2009
    Date of Patent: November 16, 2010
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Stefano Pietri, Chris C. Dao, Alfredo Olmos