Patents by Inventor Cheng-Tao Li

Cheng-Tao 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).

  • Publication number: 20240339976
    Abstract: A rail-to-rail input stage circuit including a first P-type transistor, a second P-type transistor, a first N-type transistor, a second N-type transistor, a first processing circuit, a second processing circuit, a first voltage adjustment circuit, and a second voltage adjustment circuit is provided. The first P-type transistor and the first N-type transistor are coupled to a first input terminal. The second P-type transistor and the second N-type transistor are coupled to a second input terminal. In response to the voltage of the first terminal being higher than a first threshold value, the first voltage adjustment circuit controls the operation of the first processing circuit. In response to the voltage of the first terminal being lower than a second threshold value, the second voltage adjustment circuit controls the operation of the second processing circuit.
    Type: Application
    Filed: December 30, 2023
    Publication date: October 10, 2024
    Inventor: Cheng-Tao LI
  • Publication number: 20240264622
    Abstract: A referential voltage generating device includes a bandgap-voltage generating unit, a control-comparison unit, a difference current generating unit and a referential voltage generating unit. The bandgap-voltage generating unit generates a second proportional to absolute temperature (PTAT) current and a bandgap-voltage based on a first PTAT current and a complementary to an absolute temperature (CTAT) voltage, both of which are generated in the bandgap-voltage generating unit. The control-comparison unit generates a PTAT voltage based on the second PTAT current, and generates a control voltage based on a difference voltage value between the PTAT voltage and the bandgap voltage. The difference current generating unit generates the difference current based on the control voltage, wherein the difference current is proportional to an absolute voltage value of the control voltage. The referential voltage generating unit generates a referential voltage based on the bandgap voltage and the differential current.
    Type: Application
    Filed: October 25, 2023
    Publication date: August 8, 2024
    Inventors: CHIH MING LI, CHENG-TAO LI
  • Patent number: 12047037
    Abstract: An oscillator equipped with a temperature compensation circuit is illustrated. Through the temperature compensation circuit, a transistor of a current mirror circuit of the oscillator which outputs a reference current to a voltage matching circuit is controlled by the temperature compensation voltage. Both of the temperature compensation voltage and a reference current decrease as the temperature rises, and a delay time of the oscillation voltage is proportional to the temperature compensation voltage and inversely proportional to the reference current. Therefore, the effects of temperature on the delay time just cancel each other out. The delay time of the oscillating voltage is related to the frequency of the clock signal. Therefore, if the delay time of the oscillating voltage is not affected by temperature, the frequency of the clock signal will not be affected by temperature.
    Type: Grant
    Filed: November 4, 2022
    Date of Patent: July 23, 2024
    Assignee: NUVOTON TECHNOLOGY CORPORATION
    Inventors: Cheng-Tao Li, Ping-Wen Lai
  • Publication number: 20240048130
    Abstract: A low power oscillator circuit with temperature compensation is illustrated. A current supply unit of an oscillator used to output an output current which is proportional to a reference current. As the temperature is increased, both a first threshold and the reference current of a unidirectional conduct in the temperature compensation circuit are decreased. Because a delay time of the oscillating signal is proportional to the first threshold voltage, and the delay time is inversely proportional to the reference current, the effects of the first threshold voltage and the reference current on the delay time are canceled, and the delay time of the oscillating signal is not affected by the temperature.
    Type: Application
    Filed: April 11, 2023
    Publication date: February 8, 2024
    Inventors: CHENG-TAO LI, PING-WEN LAI
  • Publication number: 20230403004
    Abstract: In a driving circuit, a drain of first NMOS transistor receives current with a positive temperature coefficient provided by current source, and a gate of first NMOS transistor and a gate of second NMOS transistor are electrically connected to the drain of first NMOS transistor. A drain and a source of second NMOS transistor respectively receive an input voltage and generate an output voltage for driving a load. Two ends of resistor are respectively electrically connected to a source of first NMOS transistor and an emitter of PNP bipolar junction transistor. A base of PNP bipolar junction transistor is electrically connected to a source of second NMOS transistor, and a collector of PNP bipolar junction transistor is electrically connected to a low voltage. By selecting the resistance value of the resistor, an overdrive voltage or a turned-on resistance value of second NMOS transistor is independent of a temperature variation.
    Type: Application
    Filed: April 20, 2023
    Publication date: December 14, 2023
    Inventors: CHENG-TAO LI, WEI-JEAN LIU
  • Publication number: 20230402998
    Abstract: A comparator module for an oscillator is disclosed. The comparator module has a function provided by two independent comparators that are combined together to share the same bias current source, so that an operation current of the oscillator may be reduced, and the circuit area and power consumption may be effectively reduced. Further, compared to the conventional design that one of the two comparators compares a first voltage with a reference voltage and the other one of the two comparators compares a second voltage with the reference voltage and the time points at which the first voltage and the second voltage are a logic high level are different, three transistors of the disclosed comparator module are designed into two equivalent differential pairs and share a bias current source.
    Type: Application
    Filed: November 2, 2022
    Publication date: December 14, 2023
    Inventors: CHENG-TAO LI, PING-WEN LAI
  • Publication number: 20230344384
    Abstract: An oscillator equipped with a temperature compensation circuit is illustrated. Through the temperature compensation circuit, a transistor of a current mirror circuit of the oscillator which outputs a reference current to a voltage matching circuit is controlled by the temperature compensation voltage. Both of the temperature compensation voltage and a reference current decrease as the temperature rises, and a delay time of the oscillation voltage is proportional to the temperature compensation voltage and inversely proportional to the reference current. Therefore, the effects of temperature on the delay time just cancel each other out. The delay time of the oscillating voltage is related to the frequency of the clock signal. Therefore, if the delay time of the oscillating voltage is not affected by temperature, the frequency of the clock signal will not be affected by temperature.
    Type: Application
    Filed: November 4, 2022
    Publication date: October 26, 2023
    Inventors: CHENG-TAO LI, Ping-Wen LAI
  • Patent number: 11736073
    Abstract: An amplifier circuit has an output stage, a first current source, a second current source, a third current source, a fourth current source, and a voltage clamping voltage. The output stage has a first P-type transistor and a first N-type transistor. The voltage clamping circuit receives a first bias voltage and a second bias voltage, and has a first end and a second end. When a second input current is positive current and the input current is a negative current or a zero current, the first end provides a first clamping voltage greater than the first bias voltage to a gate of the first P-type transistor. When the first input current is positive and the second input current is a negative current or zero current, the second end provides a second clamping voltage lower than the second bias voltage to a gate of the first N-type transistor.
    Type: Grant
    Filed: February 17, 2022
    Date of Patent: August 22, 2023
    Assignee: NUVOTON TECHNOLOGY CORPORATION
    Inventors: Po-Sheng Chen, Cheng-Tao Li
  • Patent number: 11616437
    Abstract: A constant power control circuit driving an external device receiving an input voltage and generating an output voltage is provided. A first conversion circuit converts the voltage difference between the input voltage and the output voltage to generate a charge current. An energy storage circuit is charged during a charging period by the charge current to provide a stored voltage. The charging period is terminated in response to the stored voltage reaching a predetermined voltage. A control circuit adjusts a control signal according to a length of the charging period. A second conversion circuit generates a counting voltage according to the control signal. The counting voltage is inversely proportional to the voltage difference. A third conversion circuit converts the counting voltage into a limitation current. A driving circuit compares the setting current and the limitation current to generate a driving signal and send it to the external device.
    Type: Grant
    Filed: February 11, 2021
    Date of Patent: March 28, 2023
    Assignee: NUVOTON TECHNOLOGY CORPORATION
    Inventor: Cheng-Tao Li
  • Publication number: 20230043729
    Abstract: An amplifier circuit has an output stage, a first current source, a second current source, a third current source, a fourth current source, and a voltage clamping voltage. The output stage has a first P-type transistor and a first N-type transistor. The voltage clamping circuit receives a first bias voltage and a second bias voltage, and has a first end and a second end. When a second input current is positive current and the input current is a negative current or a zero current, the first end provides a first clamping voltage greater than the first bias voltage to a gate of the first P-type transistor. When the first input current is positive and the second input current is a negative current or zero current, the second end provides a second clamping voltage lower than the second bias voltage to a gate of the first N-type transistor.
    Type: Application
    Filed: February 17, 2022
    Publication date: February 9, 2023
    Inventors: PO-SHENG CHEN, CHENG-TAO LI
  • Patent number: 11323028
    Abstract: A voltage converting apparatus includes a comparison circuit, a compensation signal generator, and a voltage converter. The comparison circuit generates a comparison result according to an output voltage, an input voltage, and a compensated feedback signal. The compensation signal generator provides a compensation signal held to be equal to a reference voltage at a first time interval in an enable period in a working cycle and sets the compensation signal to be a ramp signal at a second time interval in the enable period. The compensation signal generator generates the compensated feedback signal according to a feedback signal and the compensation signal. The voltage converter generates a control signal according to the comparison result, performs a voltage converting operation through an inductor according to the control signal, and generates the output voltage. The feedback signal is generated according to a current on the inductor.
    Type: Grant
    Filed: January 16, 2020
    Date of Patent: May 3, 2022
    Assignee: Nuvoton Technology Corporation
    Inventor: Cheng-Tao Li
  • Publication number: 20210408905
    Abstract: A constant power control circuit driving an external device receiving an input voltage and generating an output voltage is provided. A first conversion circuit converts the voltage difference between the input voltage and the output voltage to generate a charge current. An energy storage circuit is charged during a charging period by the charge current to provide a stored voltage. The charging period is terminated in response to the stored voltage reaching a predetermined voltage. A control circuit adjusts a control signal according to a length of the charging period. A second conversion circuit generates a counting voltage according to the control signal. The counting voltage is inversely proportional to the voltage difference. A third conversion circuit converts the counting voltage into a limitation current. A driving circuit compares the setting current and the limitation current to generate a driving signal and send it to the external device.
    Type: Application
    Filed: February 11, 2021
    Publication date: December 30, 2021
    Inventor: Cheng-Tao LI
  • Publication number: 20200274444
    Abstract: A voltage converting apparatus includes a comparison circuit, a compensation signal generator, and a voltage converter. The comparison circuit generates a comparison result according to an output voltage, an input voltage, and a compensated feedback signal. The compensation signal generator provides a compensation signal held to be equal to a reference voltage at a first time interval in an enable period in a working cycle and sets the compensation signal to be a ramp signal at a second time interval in the enable period. The compensation signal generator generates the compensated feedback signal according to a feedback signal and the compensation signal. The voltage converter generates a control signal according to the comparison result, performs a voltage converting operation through an inductor according to the control signal, and generates the output voltage. The feedback signal is generated according to a current on the inductor.
    Type: Application
    Filed: January 16, 2020
    Publication date: August 27, 2020
    Applicant: Nuvoton Technology Corporation
    Inventor: Cheng-Tao Li
  • Patent number: 10700509
    Abstract: A power switching device is provided. A first transmitting switch transmits an input voltage to an output node when the first transmitting switch is turned on. When the current passing through the first transmitting switch exceeds a predetermined value, a current limiting circuit turns off the first transmitting switch. When a short circuit occurs between the output node and a ground node, a short protection circuit turns off the first transmitting switch. The short protection circuit includes a first comparator and a first set circuit. The first comparator compares a voltage of the output node and a first reference voltage to generate a first comparison result to turn off the first transmitting switch. The first set circuit generates the first reference voltage according to the voltage of the output node. The first reference voltage is less than the voltage of the output node.
    Type: Grant
    Filed: December 4, 2017
    Date of Patent: June 30, 2020
    Assignee: NUVOTON TECHNOLOGY CORPORATION
    Inventor: Cheng-Tao Li
  • Publication number: 20180191149
    Abstract: A power switching device is provided. A first transmitting switch transmits an input voltage to an output node when the first transmitting switch is turned on. When the current passing through the first transmitting switch exceeds a predetermined value, a current limiting circuit turns off the first transmitting switch. When a short circuit occurs between the output node and a ground node, a short protection circuit turns off the first transmitting switch. The short protection circuit includes a first comparator and a first set circuit. The first comparator compares a voltage of the output node and a first reference voltage to generate a first comparison result to turn off the first transmitting switch. The first set circuit generates the first reference voltage according to the voltage of the output node. The first reference voltage is less than the voltage of the output node.
    Type: Application
    Filed: December 4, 2017
    Publication date: July 5, 2018
    Inventor: Cheng-Tao LI
  • Patent number: 9787116
    Abstract: A charging circuit including a transformer, a storage element, a switch element, a first resistor, and a current detection unit is provided. The transformer includes a primary coil and a secondary coil. The storage element is coupled to the secondary coil. The switch element is coupled to the primary coil. The first resistor is coupled to the primary coil. The current detection unit detects current flowing through the first resistor. When the current reaches a set current, the current detection unit sends a full signal to de-activate the switch unit.
    Type: Grant
    Filed: March 17, 2015
    Date of Patent: October 10, 2017
    Assignee: Nuvoton Technology Corporation
    Inventor: Cheng-Tao Li
  • Patent number: 9773629
    Abstract: A magnetic sensing switch includes switch body having a hollow tube and an opening. A magnetic reed switch is disposed in the tube and includes two conductive points. The plug having an elastic clamping force is fixed in the opening by interference fit. The plug including a sealant injection portion and a retaining portion communicating with the tube. The two wires are inserted in the tube, one end of each wire is connected to one conductive point, and the other end passes through the retaining portion to protrude out of the tube. A sealant is injected into the tube via the sealant injection portion to entirely wrap the magnetic reed switch and the wires inside the tube, and the sealant partially protrudes out of the sealant injection portion.
    Type: Grant
    Filed: November 9, 2016
    Date of Patent: September 26, 2017
    Assignee: FINETEK CO., LTD.
    Inventors: Ting-Kuo Wu, Chih-Wen Wang, Cheng-Tao Li
  • Publication number: 20160064981
    Abstract: A charging circuit including a transformer, a storage element, a switch element, a first resistor, and a current detection unit is provided. The transformer includes a primary coil and a secondary coil. The storage element is coupled to the secondary coil. The switch element is coupled to the primary coil. The first resistor is coupled to the primary coil. The current detection unit detects current flowing through the first resistor. When the current reaches a set current, the current detection unit sends a full signal to de-activate the switch unit.
    Type: Application
    Filed: March 17, 2015
    Publication date: March 3, 2016
    Inventor: Cheng-Tao LI
  • Patent number: 8497663
    Abstract: A charging device for providing an output voltage to charge a flash capacitor is provided. A transformer includes a primary winding and a secondary winding. The transformer generates a primary voltage according to an input voltage and generates a secondary voltage according to the primary voltage. A diode coupled between the secondary winding of the transformer and the flash capacitor provides the output voltage according to the secondary voltage. A current detector detects a current flowing through the primary winding of the transformer and generates a detection signal. A determining circuit generates a determining signal according to the primary voltage, the secondary voltage and a reference voltage. A control circuit switches a switch coupled between the primary winding of the transformer and a ground according to the detection signal and the determining signal, so as to control the transformer to charge the flash capacitor.
    Type: Grant
    Filed: April 28, 2010
    Date of Patent: July 30, 2013
    Assignee: UPI Semiconductor Corporation
    Inventors: Cheng-Tao Li, Yu-Ching Lin
  • Publication number: 20110101926
    Abstract: A charging device for providing an output voltage to charge a flash capacitor is provided. A transformer includes a primary winding and a secondary winding. The transformer generates a primary voltage according to an input voltage and generates a secondary voltage according to the primary voltage. A diode coupled between the secondary winding of the transformer and the flash capacitor provides the output voltage according to the secondary voltage. A current detector detects a current flowing through the primary winding of the transformer and generates a detection signal. A determining circuit generates a determining signal according to the primary voltage, the secondary voltage and a reference voltage. A control circuit switches a switch coupled between the primary winding of the transformer and a ground according to the detection signal and the determining signal, so as to control the transformer to charge the flash capacitor.
    Type: Application
    Filed: April 28, 2010
    Publication date: May 5, 2011
    Inventors: Cheng-Tao LI, Yu-Ching Lin