Patents by Inventor Duc Chu

Duc Chu 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: 10271448
    Abstract: Systems and methods are disclosed herein for a low cost, compact size, and thin half-etched leadframe quad-flat no-leads (QFN) package that integrates RF passive elements in the QFN leadframe for linearized PA design and RF FEMs. The integrated RF passive elements in the QFN leadframe may include RF inductors (e.g., meanders lines or spirals) for amplifier bias or RF matching, extension bar of the ground paddle for inter-stage matching or jumper pads for connection. The integrated RF passive elements may also include transmission lines for output power matching, coupled line structures such as RF couplers, RF divider or combiner realized using transmission lines with proper impedance and length, jumper pads for adjusting the bond wire length, etc. The RF parameters of the integrated passive elements are adjustable using different length and number of wire bond for fine tuning the performance of the PAM or the RF FEM.
    Type: Grant
    Filed: August 6, 2013
    Date of Patent: April 23, 2019
    Assignee: INVESTAR CORPORATION
    Inventors: Cindy Yuen, Duc Chu
  • Publication number: 20140036471
    Abstract: Systems and methods are disclosed herein for a low cost, compact size, and thin half-etched leadframe quad-flat no-leads (QFN) package that integrates RF passive elements in the QFN leadframe for linearized PA design and RF FEMs. The integrated RF passive elements in the QFN leadframe may include RF inductors (e.g., meanders lines or spirals) for amplifier bias or RF matching, extension bar of the ground paddle for inter-stage matching or jumper pads for connection. The integrated RF passive elements may also include transmission lines for output power matching, coupled line structures such as RF couplers, RF divider or combiner realized using transmission lines with proper impedance and length, jumper pads for adjusting the bond wire length, etc. The RF parameters of the integrated passive elements are adjustable using different length and number of wire bond for fine tuning the performance of the PAM or the RF FEM.
    Type: Application
    Filed: August 6, 2013
    Publication date: February 6, 2014
    Inventors: Cindy Yuen, Duc Chu
  • Patent number: 8593224
    Abstract: An improved regulator circuit, temperature compensation bias circuit, and amplifier circuit are disclosed.
    Type: Grant
    Filed: June 4, 2012
    Date of Patent: November 26, 2013
    Assignees: EpicCom, Inc., Epic Communications, Inc.
    Inventors: Cindy Yuen, Duc Chu, Kirk Laursen
  • Patent number: 8228122
    Abstract: An improved regulator circuit, temperature compensation bias circuit, and amplifier circuit are disclosed.
    Type: Grant
    Filed: May 28, 2010
    Date of Patent: July 24, 2012
    Assignees: EpicCom, Inc., Epic Communications, Inc.
    Inventors: Cindy Yuen, Duc Chu, Kirk Laursen
  • Patent number: 7863983
    Abstract: A power amplifier subsystem that includes a first stage amplifier and a second stage amplifier. A first bias circuit is coupled to the first stage amplifier, and the first bias circuit has a variable impedance that increases with radio frequency (RF) power. A second bias circuit is coupled to the second stage amplifier, and the second bias circuit has impedance relatively fixed with respect to radio frequency (RF) power. According to an embodiment of the invention, the first bias circuit comprises a transistor having a collector current that increases as radio frequency (RF) power increases. The second bias circuit can have a relatively fixed impedance. A method of designing an amplifier subsystem, where transistor size and resistor values are selected to obtain the desired bias and linearity characteristics, or transistor size and resistor values are selected to operate within a selected range, and amplifier performance is adjusted by changing the bias control voltage.
    Type: Grant
    Filed: May 19, 2004
    Date of Patent: January 4, 2011
    Assignee: Epic Communications, Inc.
    Inventors: Cindy Yuen, Kirk Laursen, Duc Chu
  • Publication number: 20090174475
    Abstract: A power amplifier subsystem that includes a first stage amplifier and a second stage amplifier. A first bias circuit is coupled to the first stage amplifier, and the first bias circuit has a variable impedance that increases with radio frequency (RF) power. A second bias circuit is coupled to the second stage amplifier, and the second bias circuit has impedance relatively fixed with respect to radio frequency (RF) power. According to an embodiment of the invention, the first bias circuit comprises a transistor having a collector current that increases as radio frequency (RF) power increases. The second bias circuit can have a relatively fixed impedance. A method of designing an amplifier subsystem, where transistor size and resistor values are selected to obtain the desired bias and linearity characteristics, or transistor size and resistor values are selected to operate within a selected range, and amplifier performance is adjusted by changing the bias control voltage.
    Type: Application
    Filed: May 19, 2004
    Publication date: July 9, 2009
    Applicant: Epic Communications, Inc.
    Inventors: Cindy Yuen, Kirk Laursen, Duc Chu