Patents by Inventor Changhua CAO

Changhua CAO 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: 10476451
    Abstract: A class-F power amplifier (PA) with a matching network is disclosed herein. The class-F PA comprises a first switch and a second switch operating in differential mode, with a second harmonic trap circuitry selectively terminating the drain terminals to ground at a second harmonic frequency. The second harmonic trap circuitry comprises a plurality of lumped inductive and capacitive components. The PA further comprises a common mode trap and a matching network to reduce the imbalance of the drain terminal impedance between first harmonics and third harmonics.
    Type: Grant
    Filed: January 16, 2018
    Date of Patent: November 12, 2019
    Assignee: MediaTek Inc.
    Inventors: Xiaochuan Guo, Jenwei Ko, Wen-Chang Lee, Changhua Cao, Caiyi Wang
  • Publication number: 20180205349
    Abstract: A class-F power amplifier (PA) with a matching network is disclosed herein. The class-F PA comprises a first switch and a second switch operating in differential mode, with a second harmonic trap circuitry selectively terminating the drain terminals to ground at a second harmonic frequency. The second harmonic trap circuitry comprises a plurality of lumped inductive and capacitive components. The PA further comprises a common mode trap and a matching network to reduce the imbalance of the drain terminal impedance between first harmonics and third harmonics.
    Type: Application
    Filed: January 16, 2018
    Publication date: July 19, 2018
    Inventors: Xiaochuan Guo, Jenwei Ko, Wen-Chang Lee, Changhua Cao, Caiyi Wang
  • Patent number: 8531322
    Abstract: Embodiments of a time-to-digital converter are provided, comprising a delay stage matrix and a measurement circuit. The delay stage matrix comprises a first and a second delay lines coupled thereto, and is arranged to propagate a transition signal from a starting delay stage in the first and a second delay lines, wherein each of the first and second delay lines comprises a same number of delay stages coupled in series, each delay stage in one of the first and second delay lines is coupled to a corresponding delay stage in the other delay line and operative to generate a delayed signal. The measurement circuit is arranged to determine a time of the transition signal propagating along the delay stages by sampling the delayed signals using a measurement signal to generate and hold a digital representation of the time.
    Type: Grant
    Filed: April 18, 2012
    Date of Patent: September 10, 2013
    Assignee: Mediatek Singapore Pte. Ltd.
    Inventors: Changhua Cao, Xiaochuan Guo, Yen-Horng Chen, Caiyi Wang
  • Publication number: 20120319883
    Abstract: Embodiments of a time-to-digital converter are provided, comprising a delay stage matrix and a measurement circuit. The delay stage matrix comprises a first and a second delay lines coupled thereto, and is arranged to propagate a transition signal from a starting delay stage in the first and a second delay lines, wherein each of the first and second delay lines comprises a same number of delay stages coupled in series, each delay stage in one of the first and second delay lines is coupled to a corresponding delay stage in the other delay line and operative to generate a delayed signal. The measurement circuit is arranged to determine a time of the transition signal propagating along the delay stages by sampling the delayed signals using a measurement signal to generate and hold a digital representation of the time.
    Type: Application
    Filed: April 18, 2012
    Publication date: December 20, 2012
    Applicant: MEDIATEK SINGAPORE PTE. LTD.
    Inventors: Changhua CAO, Xiaochuan GUO, Yen-Horng CHEN, Caiyi WANG