Patents by Inventor Wan Tim Chan

Wan Tim Chan 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: 11245391
    Abstract: Described herein are multiple designs for an improved analog switch for use in transmitting high voltage signals without using high voltage power supplies for the switch. The analog switches are able to pass and block input signals in the approximate range of ?100 V to +100 V. The use of translinear loops and a bootstrap configuration results in a constant on-resistance of the symmetrical switches and matches the conductance of each analog switch to the transconductance of an NMOS transistor, which can be easily stabilized with a constant gm biasing scheme. In certain embodiments, a shunt termination (T-switch) configuration is used for better off-isolation, and each of the symmetrical switches has its own translinear loop and thus flexibility of on-resistance and termination voltage.
    Type: Grant
    Filed: July 20, 2020
    Date of Patent: February 8, 2022
    Assignee: MICROCHIP TECHNOLOGY INC.
    Inventors: Isaac Ko, Ka Wai Ho, Wan Tim Chan, Jimes Lei
  • Publication number: 20210367500
    Abstract: Disclosed herein is a method. An output voltage level is sensed. Determining if a power source delivers power to a system. If the output voltage is higher than a designed voltage threshold (Vh), then the power source will stop delivery of power to a circuit. If the output voltage is lower than another voltage threshold (Vl), the power source transfers power to the system until the output voltage reaches the designed voltage threshold (Vh).
    Type: Application
    Filed: May 19, 2020
    Publication date: November 25, 2021
    Inventors: Ka Wai Ho, Wan Tim Chan, Ngai Wa Wong, Chiu Sing Celement Tse
  • Publication number: 20210175796
    Abstract: Disclosed herein is a fast voltage stabilizer wherein an actual voltage across a targeted electronic element is sensed. The actual voltage is compared with a reference voltage. A control signal is generated, wherein in response to the control signal, an external current path is provided to maintain current flow and stabilize the actual voltage through charging or discharging an input capacitor and a supply filtering capacitor. Under an arbitrary supply voltage variation, a fast dynamic response to regulate the voltage across the targeted electronic element is provided no matter what the operating mode of the entire electrical circuit is, including but not limited by constant current mode, constant output resistant mode and constant power mode.
    Type: Application
    Filed: December 6, 2019
    Publication date: June 10, 2021
    Inventors: Ka Wai Ho, Chung Pui Tung, Po Wa Chow, Wing To Fan, Wan Tim Chan, Ke Wei Wang, Shu Hung Henry Chung, Chiu Sing Celement Tse
  • Publication number: 20200350901
    Abstract: Described herein are multiple designs for an improved analog switch for use in transmitting high voltage signals without using high voltage power supplies for the switch. The analog switches are able to pass and block input signals in the approximate range of ?100 V to +100 V. The use of translinear loops and a bootstrap configuration results in a constant on-resistance of the symmetrical switches and matches the conductance of each analog switch to the transconductance of an NMOS transistor, which can be easily stabilized with a constant gm biasing scheme. In certain embodiments, a shunt termination (T-switch) configuration is used for better off-isolation, and each of the symmetrical switches has its own translinear loop and thus flexibility of on-resistance and termination voltage.
    Type: Application
    Filed: July 20, 2020
    Publication date: November 5, 2020
    Inventors: Isaac Ko, KA WAI HO, WAN TIM CHAN, JIMES LEI
  • Patent number: 10756719
    Abstract: Described herein are multiple designs for an improved analog switch for use in transmitting high voltage signals without using high voltage power supplies for the switch. The analog switches are able to pass and block input signals in the approximate range of ?100V to +100V. The use of translinear loops and a bootstrap configuration results in a constant on-resistance of the symmetrical switches and matches the conductance of each analog switch to the transconductance of an NMOS transistor, which can be easily stabilized with a constant gm biasing scheme. In certain embodiments, a shunt termination (T-switch) configuration is used for better off-isolation, and each of the symmetrical switches has its own translinear loop and thus flexibility of on-resistance and termination voltage.
    Type: Grant
    Filed: October 21, 2015
    Date of Patent: August 25, 2020
    Assignee: MICROCHIP TECHNOLOGY INC.
    Inventors: Isaac Ko, Ka Wai Ho, Wan Tim Chan, Jimes Lei
  • Patent number: 10637358
    Abstract: A current control circuit having a current regulation element, a first control circuit, and a second control circuit. The first control circuit is arranged to regulate, based on a reference current, a current flowing with respect to the current regulation element. The second control circuit is arranged to regulate, based on a reference voltage, a voltage across the current regulation element.
    Type: Grant
    Filed: December 18, 2017
    Date of Patent: April 28, 2020
    Assignee: Mosway Semiconductor Limited
    Inventors: Ka Wai Ho, Chung Pui Tung, Po Wa Chow, Wing To Fan, Wan Tim Chan, Shu Hung Henry Chung, Chiu Sing Tse
  • Patent number: 10468869
    Abstract: An analog transmit/receive switch and voltage detection circuit that do not require depletion mode devices are provided. The switch may be configured to operate in a receive mode and a protection mode. The voltage detection circuit may be coupled to the switch and may be configured to measure a potential difference between two terminals of the switch. The switch and the voltage detection circuit may not include any depletion mode devices.
    Type: Grant
    Filed: March 17, 2017
    Date of Patent: November 5, 2019
    Assignee: Microchip Technology Incorporated
    Inventors: Isaac Ko, Ka Wai Ho, Wan Tim Chan
  • Patent number: 10469043
    Abstract: An ultrasound probe buffer is provided. The ultrasound probe buffer may include a high impedance amplifier having a common-source core stage with series-series local feedback. The high impedance amplifier may include a first MOSFET and a second MOSFET, wherein a source terminal of the first MOSFET is coupled to a source terminal of the second MOSFET.
    Type: Grant
    Filed: March 17, 2017
    Date of Patent: November 5, 2019
    Assignee: Microchip Technology Incorporated
    Inventors: Isaac Ko, Ka Wai Ho, Wan Tim Chan
  • Publication number: 20190190389
    Abstract: A current control circuit having a current regulation element, a first control circuit, and a second control circuit. The first control circuit is arranged to regulate, based on a reference current, a current flowing with respect to the current regulation element. The second control circuit is arranged to regulate, based on a reference voltage, a voltage across the current regulation element.
    Type: Application
    Filed: December 18, 2017
    Publication date: June 20, 2019
    Inventors: Ka Wai HO, Chung Pui TUNG, Po Wa CHOW, Wing To FAN, Wan Tim CHAN, Shu Hung Henry CHUNG, Chiu Sing TSE
  • Patent number: 10171072
    Abstract: An improved analog switch for use in an ultrasound elastography probe is disclosed. The improved analog switch results in less heat dissipation compared to prior art analog switches.
    Type: Grant
    Filed: September 14, 2016
    Date of Patent: January 1, 2019
    Assignee: MICROCHIP TECHNOLOGY INC.
    Inventors: Isaac Ko, Ka Wai Ho, Wan Tim Chan
  • Publication number: 20170279263
    Abstract: An analog transmit/receive switch and voltage detection circuit that do not require depletion mode devices are provided. The switch may be configured to operate in a receive mode and a protection mode. The voltage detection circuit may be coupled to the switch and may be configured to measure a potential difference between two terminals of the switch. The switch and the voltage detection circuit may not include any depletion mode devices.
    Type: Application
    Filed: March 17, 2017
    Publication date: September 28, 2017
    Applicant: Microchip Technology Incorporated
    Inventors: Isaac Ko, Ka Wai Ho, Wan Tim Chan
  • Publication number: 20170279423
    Abstract: An ultrasound probe buffer is provided. The ultrasound probe buffer may include a high impedance amplifier having a common-source core stage with series-series local feedback. The high impedance amplifier may include a first MOSFET and a second MOSFET, wherein a source terminal of the first MOSFET is coupled to a source terminal of the second MOSFET.
    Type: Application
    Filed: March 17, 2017
    Publication date: September 28, 2017
    Applicant: Microchip Technology Incorporated
    Inventors: Isaac Ko, Ka Wai Ho, Wan Tim Chan
  • Publication number: 20170104481
    Abstract: An improved analog switch for use in an ultrasound elastography probe is disclosed. The improved analog switch results in less heat dissipation compared to prior art analog switches.
    Type: Application
    Filed: September 14, 2016
    Publication date: April 13, 2017
    Inventors: Isaac Ko, Ka Wai Ho, Wan Tim Chan
  • Publication number: 20160191036
    Abstract: Described herein are multiple designs for an improved analog switch for use in transmitting high voltage signals without using high voltage power supplies for the switch. The analog switches are able to pass and block input signals in the approximate range of ?100V to +100V. The use of translinear loops and a bootstrap configuration results in a constant on-resistance of the symmetrical switches and matches the conductance of each analog switch to the transconductance of an NMOS transistor, which can be easily stabilized with a constant gm biasing scheme. In certain embodiments, a shunt termination (T-switch) configuration is used for better off-isolation, and each of the symmetrical switches has its own translinear loop and thus flexibility of on-resistance and termination voltage.
    Type: Application
    Filed: October 21, 2015
    Publication date: June 30, 2016
    Inventors: Isaac Ko, Ka Wai Ho, Wan Tim Chan, Jimes Lei
  • Patent number: 8937565
    Abstract: An impedance matching transmission circuit for a transducer has a transmission medium connected to the transducer. A transmitting circuit is connected to the transmission medium with the transmitting circuit terminating in a reference circuit element. The transmitting circuit comprises an analog to digital converter having an analog input connected to the reference circuit element, and having a digital output. A digital to analog converter receives the digital output and generates an analog output signal in response thereto. A driver circuit is connected to the transmission medium and receives the analog output signal and supplies a driver signal to the transmission medium.
    Type: Grant
    Filed: August 22, 2012
    Date of Patent: January 20, 2015
    Assignee: Supertex, Inc.
    Inventors: Isaac Terasuth Ko, Ka Wai Ho, Wan Tim Chan
  • Publication number: 20120313485
    Abstract: An impedance matching transmission circuit for a transducer has a transmission medium connected to the transducer. A transmitting circuit is connected to the transmission medium with the transmitting circuit terminating in a reference circuit element. The transmitting circuit comprises an analog to digital converter having an analog input connected to the reference circuit element, and having a digital output. A digital to analog converter receives the digital output and generates an analog output signal in response thereto. A driver circuit is connected to the transmission medium and receives the analog output signal and supplies a driver signal to the transmission medium.
    Type: Application
    Filed: August 22, 2012
    Publication date: December 13, 2012
    Applicant: Supertex, Inc.
    Inventors: Isaac Terasuth KO, Ka Wai HO, Wan Tim CHAN
  • Patent number: 8269656
    Abstract: An impedance matching transmission circuit for a transducer has a transmission medium connected to the transducer. A transmitting circuit is connected to the transmission medium with the transmitting circuit terminating in a reference circuit element. The transmitting circuit comprises an analog to digital converter having an analog input connected to the reference circuit element, and having a digital output. A digital to analog converter receives the digital output and generates an analog output signal in response thereto. A driver circuit is connected to the transmission medium and receives the analog output signal and supplies a driver signal to the transmission medium.
    Type: Grant
    Filed: May 24, 2010
    Date of Patent: September 18, 2012
    Assignee: Supertex, Inc.
    Inventors: Isaac Terasuth Ko, Ka Wai Ho, Wan Tim Chan
  • Patent number: 8193839
    Abstract: A multi-level transmitter circuit with substantially constant output impedance has a capacitive transducer connected between a voltage input and ground. A first voltage path connects the voltage input to a first positive voltage source. The first voltage path is controlled by a first control signal. A second voltage path connects the voltage input to a second positive voltage source, less than the first positive voltage source. The second voltage path passes through a diode and is controlled by a second control signal. A third voltage path connects the voltage input to a third voltage source, less than ground, and is controlled by the second control signal. The impedance at the voltage input during the first control signal is substantially the same as the impedance at the voltage input during the second control signal.
    Type: Grant
    Filed: May 24, 2010
    Date of Patent: June 5, 2012
    Assignee: SuperTex, Inc.
    Inventors: Isaac Terasuth Ko, Ka Wai Ho, Wan Tim Chan
  • Publication number: 20110285457
    Abstract: A multi-level transmitter circuit with substantially constant output impedance has a capacitive transducer connected between a voltage input and ground. A first voltage path connects the voltage input to a first positive voltage source. The first voltage path is controlled by a first control signal. A second voltage path connects the voltage input to a second positive voltage source, less than the first positive voltage source. The second voltage path passes through a diode and is controlled by a second control signal. A third voltage path connects the voltage input to a third voltage source, less than ground, and is controlled by the second control signal. The impedance at the voltage input during the first control signal is substantially the same as the impedance at the voltage input during the second control signal.
    Type: Application
    Filed: May 24, 2010
    Publication date: November 24, 2011
    Inventors: Isaac Terasuth Ko, Ka Wai Ho, Wan Tim Chan
  • Publication number: 20110285561
    Abstract: An impedance matching transmission circuit for a transducer has a transmission medium connected to the transducer. A transmitting circuit is connected to the transmission medium with the transmitting circuit terminating in a reference circuit element. The transmitting circuit comprises an analog to digital converter having an analog input connected to the reference circuit element, and having a digital output. A digital to analog converter receives the digital output and generates an analog output signal in response thereto. A driver circuit is connected to the transmission medium and receives the analog output signal and supplies a driver signal to the transmission medium.
    Type: Application
    Filed: May 24, 2010
    Publication date: November 24, 2011
    Inventors: Isaac Terasuth Ko, Ka Wai Ho, Wan Tim Chan