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).
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Publication number: 20140266098Abstract: 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: ApplicationFiled: March 14, 2013Publication date: September 18, 2014Inventors: Chris C. Dao, Stefano Pietri, Juxiang Ren
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Publication number: 20140203794Abstract: 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: ApplicationFiled: January 24, 2013Publication date: July 24, 2014Inventors: STEFANO PIETRI, Chris C. Dao, Juxiang Ren
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Publication number: 20140118036Abstract: 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: ApplicationFiled: December 13, 2013Publication date: May 1, 2014Applicants: FREESCALE SEMICONDUCTOR, INC., STMICROELECTRONICS PRIVATE LTD., STMICROELECTRONICS SRLInventors: Stefano Pietri, Chris C. Dao, Juxiang Ren, Nicolas Grossier, V. Srinivasan
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Patent number: 8629713Abstract: 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: GrantFiled: May 29, 2012Date of Patent: January 14, 2014Assignees: Freescale Semiconductor, Inc., STMicroelectronics SRL, STMicroelectronics Private Ltd.Inventors: Stefano Pietri, Chris C. Dao, Juxiang Ren, Nicolas Grosssier, V Srinivasan
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Publication number: 20130321071Abstract: 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: ApplicationFiled: May 29, 2012Publication date: December 5, 2013Applicants: FREESCALE SEMICONDUCTOR, INC., STMICROELECTRONICS PRIVATE LTD., STMICROELECTRONICS SRLInventors: Stefano Pietri, Chris C. Dao, Juxiang Ren, Nicolas Grossier, V. Srinivasan
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Patent number: 8552700Abstract: 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: GrantFiled: October 6, 2010Date of Patent: October 8, 2013Assignee: Freescale Semiconductor, Inc.Inventors: Chris C. Dao, Stefano Pietri, Juxiang Ren
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Publication number: 20130234743Abstract: 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: ApplicationFiled: March 7, 2012Publication date: September 12, 2013Applicant: FREESCALE SEMICONDUCTOR, INC.Inventors: Juxiang Ren, Chris C. Dao, Stefano Pietri
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Patent number: 8456784Abstract: 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: GrantFiled: May 3, 2010Date of Patent: June 4, 2013Assignee: Freescale Semiconductor, Inc.Inventors: Michael A. Stockinger, Chris C. Dao, Dale J. McQuirk
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Publication number: 20130113449Abstract: 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: ApplicationFiled: November 4, 2011Publication date: May 9, 2013Inventors: Stefano Pietri, Chris C. Dao, Garrin S. Felber
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Patent number: 8362814Abstract: 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: GrantFiled: July 19, 2012Date of Patent: January 29, 2013Assignee: Freescale Semiconductor, Inc.Inventors: Chris C. Dao, Stefano Pietri, Andre Luis Vilas Boas
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Publication number: 20120281491Abstract: 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: ApplicationFiled: July 19, 2012Publication date: November 8, 2012Applicant: FREESCALE SEMICONDUCTOR, INC.Inventors: Chris C. Dao, Stefano Pietri, Andre Luis Vilas Boas
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Patent number: 8253453Abstract: 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: GrantFiled: October 28, 2010Date of Patent: August 28, 2012Assignee: Freescale Semiconductor, Inc.Inventors: Andre Luis Vilas Boas, Chris C. Dao, Stefano Pietri
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Patent number: 8228100Abstract: 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: GrantFiled: January 26, 2010Date of Patent: July 24, 2012Assignee: Freescale Semiconductor, Inc.Inventors: Chris C. Dao, Stefano Pietri, Andre Luis Vilas Boas
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Publication number: 20120105108Abstract: 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: ApplicationFiled: October 28, 2010Publication date: May 3, 2012Applicant: Freescale Semiconductor, Inc.Inventors: Andre Luis Vilas Boas, Chris C. Dao, Stefano Pietri
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Publication number: 20120086423Abstract: 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: ApplicationFiled: October 6, 2010Publication date: April 12, 2012Inventors: Chris C. Dao, Stefano Pietri, Juxiang Ren
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Publication number: 20110267723Abstract: 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: ApplicationFiled: May 3, 2010Publication date: November 3, 2011Inventors: Michael A. Stockinger, Chris C. Dao, Dale J. McQuirk
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Publication number: 20110185212Abstract: 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: ApplicationFiled: January 26, 2010Publication date: July 28, 2011Inventors: CHRIS C. DAO, Stefano Pietri, Andre Luis Vilas Boas
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Patent number: 7924108Abstract: 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: GrantFiled: August 14, 2009Date of Patent: April 12, 2011Assignee: Freescale Semiconductor, Inc.Inventors: Chris C. Dao, Stefano Pietri, Wenzhong Zhang
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Publication number: 20110037524Abstract: 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: ApplicationFiled: August 14, 2009Publication date: February 17, 2011Inventors: Chris C. Dao, Stefano Pietri, Wenzhong Zhang
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Patent number: 7834689Abstract: 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: GrantFiled: July 22, 2009Date of Patent: November 16, 2010Assignee: Freescale Semiconductor, Inc.Inventors: Stefano Pietri, Chris C. Dao, Alfredo Olmos