Patents by Inventor San Hwa Chee
San Hwa Chee 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: 20240136938Abstract: An AC-DC converter includes an AC voltage source, a rectifier, and a rectifier control circuit. The rectifier includes a field effect transistor (FET) having a source, a drain, and a gate. The drain of the FET is coupled to the AC voltage source, and the source is coupled to ground. The rectifier control circuit is coupled to the gate of the FET. The rectifier control circuit is configured to provide a ramp voltage to regulate the FET after the AC voltage source is turned off.Type: ApplicationFiled: October 20, 2022Publication date: April 25, 2024Inventors: Wenbo LIANG, Edward Er DENG, Ying LI, San Hwa CHEE
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Patent number: 11581796Abstract: Pulse width modulation (PWM) controllers for hybrid converters are provided herein. In certain embodiments, a PWM controller for a hybrid converter includes a threshold generation circuit for generating a threshold signal based on an output voltage of the hybrid converter, a threshold adjustment circuit for generating an adjusted threshold signal based on sensing a voltage of a flying capacitor of the hybrid converter, and a comparator that generates a comparison signal based on comparing the adjusted threshold signal to an indication of an inductor current of the hybrid converter. The output of the comparator is used for generating PWM control signals used for turning on and off the switches (for instance, power transistors) of the hybrid converter.Type: GrantFiled: January 19, 2021Date of Patent: February 14, 2023Assignee: Analog Devices, Inc.Inventors: Yingyi Yan, San Hwa Chee
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Patent number: 11545886Abstract: Pulse width modulation (PWM) controllers for hybrid converters are provided herein. In certain embodiments, a PWM controller for a hybrid converter includes a threshold generation circuit for generating a threshold signal based on an output voltage of the hybrid converter, a threshold adjustment circuit for generating an adjusted threshold signal based on sensing a voltage of a flying capacitor of the hybrid converter, and a comparator that generates a comparison signal based on comparing the adjusted threshold signal to an indication of an inductor current of the hybrid converter. The output of the comparator is used for generating PWM control signals used for turning on and off the switches (for instance, power transistors) of the hybrid converter.Type: GrantFiled: January 19, 2021Date of Patent: January 3, 2023Assignee: Analog Devices, Inc.Inventors: Yingyi Yan, San Hwa Chee
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Publication number: 20220231618Abstract: Pulse width modulation (PWM) controllers for hybrid converters are provided herein. In certain embodiments, a PWM controller for a hybrid converter includes a threshold generation circuit for generating a threshold signal based on an output voltage of the hybrid converter, a threshold adjustment circuit for generating an adjusted threshold signal based on sensing a voltage of a flying capacitor of the hybrid converter, and a comparator that generates a comparison signal based on comparing the adjusted threshold signal to an indication of an inductor current of the hybrid converter. The output of the comparator is used for generating PWM control signals used for turning on and off the switches (for instance, power transistors) of the hybrid converter.Type: ApplicationFiled: January 19, 2021Publication date: July 21, 2022Inventors: Yingyi Yan, San Hwa Chee
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Patent number: 10693373Abstract: A hybrid power converter includes a switching circuit, an LC circuit, and a detection circuit. The switching circuit includes three or more switching transistors in series that may turn on or off according to a switching cycle to generate a series of voltage pulses at an output port across one of the switching transistors. The LC circuit may be coupled to the output port of the switching circuit to receive the series of pulses and to generate an inductor current in the LC circuit. The inductor current may charge a capacitor of the LC circuit to generate an output voltage of the hybrid power converter. The detection circuit may be coupled to the switching circuit and may generate a low frequency portion of the inductor current based on one or more currents of the switching transistors to adjust the switching cycle based at least on the low frequency portion.Type: GrantFiled: August 24, 2018Date of Patent: June 23, 2020Assignee: Linear Technology Holding LLCInventors: Jian Li, San-Hwa Chee
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Patent number: 10666135Abstract: Methods and systems of controlling a switched capacitor converter are provided. Upon determining that a voltage across a flying capacitor is above a first threshold, a first current is drawn from a first terminal of the flying capacitor by a first current source, and a second current is provided to a second terminal of the flying capacitor by a second current source. Upon determining that the voltage across the flying capacitor is below a second threshold, the first current is provided to the first terminal of the flying capacitor by the first current source, and the second current is drawn from the second terminal of the flying capacitor by the second current source. Upon determining that the voltage across the flying capacitor is above the second threshold and below the first threshold from the reference voltage, the first and second current sources are turned OFF.Type: GrantFiled: June 11, 2018Date of Patent: May 26, 2020Assignee: Linear Technology LLCInventors: Xu Zhang, Jian Li, San Hwa Chee
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Publication number: 20200067409Abstract: A hybrid power converter includes a switching circuit, an LC circuit, and a detection circuit. The switching circuit includes three or more switching transistors in series that may turn on or off according to a switching cycle to generate a series of voltage pulses at an output port across one of the switching transistors. The LC circuit may be coupled to the output port of the switching circuit to receive the series of pulses and to generate an inductor current in the LC circuit. The inductor current may charge a capacitor of the LC circuit to generate an output voltage of the hybrid power converter. The detection circuit may be coupled to the switching circuit and may generate a low frequency portion of the inductor current based on one or more currents of the switching transistors to adjust the switching cycle based at least on the low frequency portion.Type: ApplicationFiled: August 24, 2018Publication date: February 27, 2020Inventors: Jian LI, San-Hwa CHEE
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Patent number: 10468978Abstract: Methods and systems of pre-balancing a switched capacitor converter are provided. A first comparator includes a positive input configured to receive a voltage across an output capacitor and a negative input configured to receive a first hysteresis voltage. A second comparator includes a positive input configured to receive a voltage across an input capacitor of the switched capacitor converter and a negative input configured to receive a second hysteresis voltage. A first current source is coupled between the output capacitor and GND and is configured to discharge the output capacitor upon determining that the voltage across the output capacitor is above a tolerance provided by the first hysteresis voltage. A second current source is coupled between the input capacitor and GND and is configured to discharge the input capacitor upon determining that the voltage across the input capacitor is above a tolerance provided by the second hysteresis voltage.Type: GrantFiled: March 21, 2017Date of Patent: November 5, 2019Assignee: Linear Technology CorporationInventors: Xu Zhang, Jian Li, San Hwa Chee
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Patent number: 10447152Abstract: A method and system of driving a switched capacitor converter having a plurality of switches. A first driver coupled to a first switch is powered by providing a first reference voltage level VCC to a first supply and a GND reference to a second supply node of the first driver. A second driver coupled to a second switch is powered by providing a unidirectional path between the first supply node of a first driver and the first supply node of the second driver and by keeping OFF the second switch while turning ON the first switch. A third driver coupled to a third switch is powered by providing a unidirectional path between the first supply node of a second driver and the first supply node of the third driver and by keeping OFF the first and third switch while turning ON the second switch.Type: GrantFiled: March 21, 2017Date of Patent: October 15, 2019Assignee: Linear Technology CorporationInventors: Xu Zhang, Jian Li, San Hwa Chee
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Patent number: 10389237Abstract: The subject disclosure includes reducing switching losses at lower load current while maintaining the switching frequency for a hybrid switched capacitor converter circuit. Control circuitry is coupled to the hybrid switched capacitor converter circuit and configured to measure a load current at an output of the hybrid switched capacitor converter circuit in a buck phase mode. The control circuitry is configured to compare the measured load current to set of predetermined thresholds. The control circuitry is configured to drive a first voltage to the second set of transistors that turns on the second set of transistors periodically to regulate the output during the buck phase mode. The control circuitry is also configured to drive a second voltage to the first set of transistors that turns off the first set of transistors for one or more switching cycles while the second set of transistors are turned on based on the comparison.Type: GrantFiled: April 19, 2018Date of Patent: August 20, 2019Assignee: Linear Technology Holding LLCInventors: San-Hwa Chee, Yingyi Yan
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Publication number: 20180294717Abstract: Methods and systems of controlling a switched capacitor converter are provided. Upon determining that a voltage across a flying capacitor is above a first threshold, a first current is drawn from a first terminal of the flying capacitor by a first current source, and a second current is provided to a second terminal of the flying capacitor by a second current source. Upon determining that the voltage across the flying capacitor is below a second threshold, the first current is provided to the first terminal of the flying capacitor by the first current source, and the second current is drawn from the second terminal of the flying capacitor by the second current source. Upon determining that the voltage across the flying capacitor is above the second threshold and below the first threshold from the reference voltage, the first and second current sources are turned OFF.Type: ApplicationFiled: June 11, 2018Publication date: October 11, 2018Inventors: Xu ZHANG, Jian Li, San Hwa Chee
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Patent number: 9998000Abstract: Methods and systems of controlling a switched capacitor converter are provided. Upon determining that a voltage across a flying capacitor is above a first threshold, a first current is drawn from a first terminal of the flying capacitor by a first current source, and a second current is provided to a second terminal of the flying capacitor by a second current source. Upon determining that the voltage across the flying capacitor is below a second threshold, the first current is provided to the first terminal of the flying capacitor by the first current source, and the second current is drawn from the second terminal of the flying capacitor by the second current source. Upon determining that the voltage across the flying capacitor is above the second threshold and below the first threshold from the reference voltage, the first and second current sources are turned OFF.Type: GrantFiled: March 21, 2017Date of Patent: June 12, 2018Assignee: LINEAR TECHNOLOGY CORPORATIONInventors: Xu Zhang, Jian Li, San Hwa Chee
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Publication number: 20180019669Abstract: Methods and systems of pre-balancing a switched capacitor converter are provided. A first comparator includes a positive input configured to receive a voltage across an output capacitor and a negative input configured to receive a first hysteresis voltage. A second comparator includes a positive input configured to receive a voltage across an input capacitor of the switched capacitor converter and a negative input configured to receive a second hysteresis voltage. A first current source is coupled between the output capacitor and GND and is configured to discharge the output capacitor upon determining that the voltage across the output capacitor is above a tolerance provided by the first hysteresis voltage. A second current source is coupled between the input capacitor and GND and is configured to discharge the input capacitor upon determining that the voltage across the input capacitor is above a tolerance provided by the second hysteresis voltage.Type: ApplicationFiled: March 21, 2017Publication date: January 18, 2018Inventors: Xu Zhang, Jian Li, San Hwa Chee
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Publication number: 20180019666Abstract: A method and system of driving a switched capacitor converter having a plurality of switches. A first driver coupled to a first switch is powered by providing a first reference voltage level VCC to a first supply and a GND reference to a second supply node of the first driver. A second driver coupled to a second switch is powered by providing a unidirectional path between the first supply node of a first driver and the first supply node of the second driver and by keeping OFF the second switch while turning ON the first switch. A third driver coupled to a third switch is powered by providing a unidirectional path between the first supply node of a second driver and the first supply node of the third driver and by keeping OFF the first and third switch while turning ON the second switch.Type: ApplicationFiled: March 21, 2017Publication date: January 18, 2018Inventors: Xu Zhang, Jian Li, San Hwa Chee
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Publication number: 20180019665Abstract: Methods and systems of controlling a switched capacitor converter are provided. Upon determining that a voltage across a flying capacitor is above a first threshold, a first current is drawn from a first terminal of the flying capacitor by a first current source, and a second current is provided to a second terminal of the flying capacitor by a second current source. Upon determining that the voltage across the flying capacitor is below a second threshold, the first current is provided to the first terminal of the flying capacitor by the first current source, and the second current is drawn from the second terminal of the flying capacitor by the second current source. Upon determining that the voltage across the flying capacitor is above the second threshold and below the first threshold from the reference voltage, the first and second current sources are turned OFF.Type: ApplicationFiled: March 21, 2017Publication date: January 18, 2018Inventors: Xu Zhang, Jian Li, San Hwa Chee
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Patent number: 8433078Abstract: An audio amplifier and a method of operating such an amplifier are disclosed. The audio amplifier includes a switch disabling controller and/or an output set-point controller. The switch disabling controller is configured to disable switching of an output switch circuit or other switch circuit while an input signal represents at least relative silence. The output set-point controller is configured to bring and/or hold first and second switch nodes toward and/or at a set-point voltage while the input signal represents at least relative silence.Type: GrantFiled: October 26, 2009Date of Patent: April 30, 2013Assignee: Monolithic Power Systems, Inc.Inventor: San Hwa Chee
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Patent number: 8026707Abstract: A circuit is provided including an output stage with a pair of transistors. Further provided is a control circuit in communication with the output stage. The control circuit is capable of controlling a duration in which at least one of the transistors is actuated for reducing an in-rush current.Type: GrantFiled: August 29, 2007Date of Patent: September 27, 2011Assignee: Monolithic Power Systems, Inc.Inventor: San Hwa Chee
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Publication number: 20110096944Abstract: An audio amplifier and a method of operating such an amplifier are disclosed. The audio amplifier includes a switch disabling controller and/or an output set-point controller. The switch disabling controller is configured to disable switching of an output switch circuit or other switch circuit while an input signal represents at least relative silence. The output set-point controller is configured to bring and/or hold first and second switch nodes toward and/or at a set-point voltage while the input signal represents at least relative silence.Type: ApplicationFiled: October 26, 2009Publication date: April 28, 2011Inventor: San Hwa Chee
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Publication number: 20090058378Abstract: A circuit is provided including an output stage with a pair of transistors. Further provided is a control circuit in communication with the output stage. The control circuit is capable of controlling a duration in which at least one of the transistors is actuated for reducing an in-rush current.Type: ApplicationFiled: August 29, 2007Publication date: March 5, 2009Inventor: San Hwa Chee
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Patent number: 6369665Abstract: An oscillator circuit that adjusts the oscillation voltage such that the voltage oscillates in a uniform manner independent of changes to frequency. Slope compensation is derived from the oscillation voltage. The adjustment is implemented by using a window comparator to establish a range of operation of the oscillation voltage. When the oscillation voltage is outside the range of operation, the window comparator instructs a counter circuit to either count up or count down, depending on the value of the oscillation voltage relative to the range. This counting then is used to adjust the amount of current which charges the capacitor. Thus, when the peak voltage is too low, the amount of current is adjusted upward. When the peak voltage is too high, the amount of current is adjusted downward. In this fashion, the oscillation voltage is maintained at a substantially uniform value, while the frequency is synchronized to an external clock signal.Type: GrantFiled: October 2, 2000Date of Patent: April 9, 2002Assignee: Linear Technology CorporationInventors: San Hwa Chee, Stephen W. Hobrecht, Randy Flatness