Patents by Inventor Li-Chung Chang

Li-Chung Chang 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: 20140072001
    Abstract: A receiver architecture for carrier aggregation is disclosed. In an exemplary design, an apparatus (e.g., a wireless device, a circuit module, etc.) includes a plurality of low noise amplifiers (LNAs), a plurality of switches, and at least one downconverter. The LNAs receive and amplify at least one input radio frequency (RF) signal and provide at least one amplified RF signal. The switches are coupled to the outputs of the plurality of LNAs. The at least one downconverter is coupled to the plurality of switches, downconverts the at least one amplified RF signal, and provides at least one downconverted signal. The switches reduce the number of downconverters needed to support reception of transmissions on multiple sets of carriers via multiple receive antennas. The LNAs and the switches may be implemented on at least one front-end module or a back-end module. The downconverter(s) are implemented on the back-end module.
    Type: Application
    Filed: September 11, 2012
    Publication date: March 13, 2014
    Applicant: QUALCOMM INCORPORATED
    Inventors: Li-Chung Chang, Prasad Srinivasa Siva Gudem, Frederic Bossu, Christian Holenstein
  • Publication number: 20130231064
    Abstract: A wireless communication device configured for receiving a multiple carrier signal is described. The wireless communication device includes a single-chip signal splitting carrier aggregation receiver architecture. The single-chip signal splitting carrier aggregation receiver architecture includes a primary antenna, a secondary antenna and a transceiver chip. The single-chip signal splitting carrier aggregation receiver architecture reuses a simultaneous hybrid dual receiver path.
    Type: Application
    Filed: March 2, 2012
    Publication date: September 5, 2013
    Applicant: QUALCOMM INCORPORATED
    Inventors: Prasad Srinivasa Siva Gudem, Gurkanwal Singh Sahota, Li-Chung Chang, Christian Holenstein, Frederic Bossu
  • Publication number: 20130230080
    Abstract: A wireless communication device configured for receiving a wireless multiple-input and multiple-output signal. The wireless communication device includes a first multiple-input and multiple-output carrier aggregation receiver reuse architecture. The first multiple-input and multiple-output carrier aggregation receiver reuse architecture includes a first antenna, a second antenna and a transceiver chip. The first multiple-input and multiple-output carrier aggregation receiver reuse architecture reuses a first carrier aggregation receiver path. The wireless communication device also includes a second multiple-input and multiple-output carrier aggregation receiver reuse architecture. The second multiple-input and multiple-output carrier aggregation receiver reuse architecture includes a third antenna, a fourth antenna and a receiver chip. The second multiple-input and multiple-output carrier aggregation receiver reuse architecture reuses a second carrier aggregation receiver path.
    Type: Application
    Filed: March 2, 2012
    Publication date: September 5, 2013
    Applicant: QUALCOMM INCORPORATED
    Inventors: Prasad Srinivasa Siva Gudem, Xiaoyin He, Tamer Adel Kadous, Li-Chung Chang
  • Patent number: 8526903
    Abstract: Techniques for performing transmit (TX) leakage cancellation are described. A receiver includes a low noise amplifier (LNA) and a TX leakage canceller. The LNA amplifies a receiver input signal and provides an amplified signal. The TX leakage canceller includes a downconverter, a notch filter, and an upconverter. The downconverter downconverts a canceller input signal (e.g., obtained from the LNA output) with a first LO signal at a transmit frequency and provides a downconverted signal. The notch filter filters the downconverted signal to pass an undesired signal (e.g., a TX leakage signal) and attenuate a jammer and a desired signal in the canceller input signal. The upconverter upconverts the filtered signal with a second LO signal at the transmit frequency and provides a feedback signal. The feedback signal is subtracted at the input or output of the LNA to cancel the undesired signal.
    Type: Grant
    Filed: March 11, 2008
    Date of Patent: September 3, 2013
    Assignee: QUALCOMM, Incorporated
    Inventors: Prasad S Gudem, Li-Chung Chang
  • Publication number: 20130226496
    Abstract: A system for precise calibration of electronic components is disclosed. In an exemplary embodiment, an apparatus for calibrating a tunable component on an integrated circuit chip includes an on-chip reference component configured to generate a first on-chip reference level, an on-chip connector configured to couple to an external test unit component to generate a second on-chip reference level, and an on-chip memory configured to store at least one error adjustment parameter determined from a difference between the first on-chip reference level and the second on-chip reference level, and wherein the at least one error adjustment parameter is configured to calibrate the tunable component to a desired value.
    Type: Application
    Filed: February 29, 2012
    Publication date: August 29, 2013
    Applicant: QUALCOMM Incorporated
    Inventors: Prasad S. Gudem, Bhushan Shanti Asuri, Li-Chung Chang, Vinod V. Panikkath
  • Patent number: 8433272
    Abstract: A receiver includes a jammer detector configured to detect the presence or the absence of jamming in a communication signal within a gain state. The receiver further includes an amplifier configured to amplify the communication signal in a high linearity receiving mode or a low linearity receiving mode, wherein the high linearity receiving mode corresponds with a lower gain for the gain state in the amplifier relative to that of the low linearity receiving mode. In addition, the receiver includes a processing unit coupled to the jammer detector, the processing unit being configured to control the amplifier to amplify the communication signal in either the high linearity receiving mode or the low linearity receiving mode, based on the output of the jammer detector detecting the presence or the absence of jamming in the communication signal. A method is also provided for processing a communication signal in a receiver.
    Type: Grant
    Filed: September 18, 2008
    Date of Patent: April 30, 2013
    Assignee: Qualcomm Incorporated
    Inventors: Prasad S. Gudem, Jose Cabanillas, Li-Chung Chang, Li Liu
  • Publication number: 20130003617
    Abstract: A receiver with bypass mode for improved sensitivity is disclosed. An apparatus is provided that includes a non-bypass signal path coupled to a receiver, the non-bypass signal path comprising a filter, a bypass signal path coupled to the receiver, the bypass signal path configure to bypass the filter, and a switch configured to couple an antenna to the non-bypass signal path during time intervals when signals transmitted by a related local transmitter are transmitted with a signal power that exceeds a threshold, and to couple the antenna to the bypass signal path during other time intervals. In another aspect, the switch is configured to couple the antenna to the non-bypass signal path during time intervals when a jamming signal in a selected frequency range is received with a signal power that exceeds a threshold, and to couple the antenna to the bypass signal path during other time intervals.
    Type: Application
    Filed: June 29, 2011
    Publication date: January 3, 2013
    Applicant: QUALCOMM Incorporated
    Inventors: Prasad Srinivasa Siva Gudem, Tamer Adel Kadous, Sumit Verma, Li-chung Chang
  • Publication number: 20120327825
    Abstract: A wireless communication device configured for receiving a multiple carrier signal is described. The wireless communication device includes a primary signal splitting carrier aggregation architecture. The primary signal splitting carrier aggregation architecture includes a primary antenna and a transceiver chip. The primary signal splitting carrier aggregation architecture reuses a first diversity/simultaneous hybrid dual receiver path. The wireless communication device also includes a secondary signal splitting carrier aggregation architecture. The secondary signal splitting carrier aggregation architecture includes a secondary antenna and a receiver chip. The secondary signal splitting carrier aggregation architecture reuses a second diversity/simultaneous hybrid dual receiver path.
    Type: Application
    Filed: March 2, 2012
    Publication date: December 27, 2012
    Applicant: QUALCOMM INCORPORATED
    Inventors: Prasad Srinivasa Siva Gudem, Udara C. Fernando, Li-Chung Chang
  • Patent number: 8310312
    Abstract: Amplifiers with improved linearity and noise performance are described. In an exemplary design, an apparatus includes first through sixth transistors. The first transistor receives an input signal and provides an amplified signal. The second transistor receives the amplified signal and provides signal drive for an output signal. The third transistor receives the input signal and provides an intermediate signal. The fourth transistor provides bias for the third transistor in a high linearity mode. The fifth transistor receives the intermediate signal and provides signal drive for the output signal in a low linearity mode. The third and fourth transistors form a deboost path that is enabled in the high linearity mode to improve linearity. The third and fifth transistors form a cascode path that is enabled in the low linearity mode to improve gain and noise performance. The sixth transistor generates distortion component used to cancel distortion component from the first transistor.
    Type: Grant
    Filed: August 11, 2009
    Date of Patent: November 13, 2012
    Assignee: QUALCOMM, Incorporated
    Inventors: Hanil Lee, Li-Chung Chang
  • Patent number: 8270499
    Abstract: A receiver with a balanced I/Q transformer is described. In an exemplary design, the receiver includes an LNA that amplifies a received RF signal and provides a single-ended RF signal to the balanced I/Q transformer. The balanced I/Q transformer includes at least one primary coil and first and second secondary coils. The first secondary coil is magnetically coupled to the at least one primary coil and provides a first differential RF signal to a first mixer. The second secondary coil is magnetically coupled to the at least one primary coil and provides a second differential RF signal to a second mixer. The first and second mixers downconvert the first and second differential RF signals with I and Q LO signals, respectively, and provide differential I and Q downconverted signals. The primary and secondary coils may be fabricated on two conductive layers of an integrated circuit.
    Type: Grant
    Filed: May 15, 2009
    Date of Patent: September 18, 2012
    Assignee: QUALCOMM, Incorporated
    Inventors: Li-Chung Chang, Maulin P. Bhagat, Hanil Lee, Ravi Sridhara
  • Patent number: 8036623
    Abstract: This disclosure describes techniques for reducing adverse effects of TX signal leakage in a full-duplex, wireless communication device. The techniques make use of a notch filter to reject TX signal leakage in a signal processed in the RX path of the wireless communication device. The notch filter may be constructed as a complex notch filter using passive resistor and capacitor components to produce a notch frequency that attenuates TX signal leakage components in a desired signal. The notch filter may be applied to a down-converted, baseband signal produced by a passive mixer.
    Type: Grant
    Filed: July 12, 2007
    Date of Patent: October 11, 2011
    Assignee: QUALCOMM, Incorporated
    Inventors: Li-Chung Chang, Prasad S. Gudem, Jose Cabanillas
  • Publication number: 20110110463
    Abstract: A receiver with a balanced I/Q transformer is described. In an exemplary design, the receiver includes an LNA that amplifies a received RF signal and provides a single-ended RF signal to the balanced I/Q transformer. The balanced I/Q transformer includes at least one primary coil and first and second secondary coils. The first secondary coil is magnetically coupled to the at least one primary coil and provides a first differential RF signal to a first mixer. The second secondary coil is magnetically coupled to the at least one primary coil and provides a second differential RF signal to a second mixer. The first and second mixers downconvert the first and second differential RF signals with I and Q LO signals, respectively, and provide differential I and Q downconverted signals. The primary and secondary coils may be fabricated on two conductive layers of an integrated circuit.
    Type: Application
    Filed: May 15, 2009
    Publication date: May 12, 2011
    Applicant: QUALCOMM INCORPORATED
    Inventors: Li-Chung Chang, Maulin P. Bhagat, Hanil Lee, Ravi Sridhara
  • Patent number: 7935776
    Abstract: The present invention relates to a radiation curable and developable polyurethane which is characterized by having a carboxy group in its main chain and a acryloyl group in its side chain and comprising the following repeat units (I), (II), and (II) in a random arrangement: wherein R1, R2, R3, R4, and T are defined in the specification. The polyurethane has a weight molecular weight measured by GPC in a range of from 3,000 to 400,000; an acid value in a range of from 5 to 120 mgKOH/g. The present invention also relates to a radiation curable and developable composition containing the polyurethane.
    Type: Grant
    Filed: March 20, 2008
    Date of Patent: May 3, 2011
    Assignee: AGI Corporation
    Inventors: Wei Hsiang Huang, Ying Jen Chen, Jui Ming Chang, Chun Hung Kuo, Hong Ye Lin, Li Chung Chang
  • Publication number: 20110037518
    Abstract: Amplifiers with improved linearity and noise performance are described. In an exemplary design, an apparatus includes first through sixth transistors. The first transistor receives an input signal and provides an amplified signal. The second transistor receives the amplified signal and provides signal drive for an output signal. The third transistor receives the input signal and provides an intermediate signal. The fourth transistor provides bias for the third transistor in a high linearity mode. The fifth transistor receives the intermediate signal and provides signal drive for the output signal in a low linearity mode. The third and fourth transistors form a deboost path that is enabled in the high linearity mode to improve linearity. The third and fifth transistors form a cascode path that is enabled in the low linearity mode to improve gain and noise performance. The sixth transistor generates distortion component used to cancel distortion component from the first transistor.
    Type: Application
    Filed: August 11, 2009
    Publication date: February 17, 2011
    Applicant: QUALCOMM INCORPORATED
    Inventors: Hanil Lee, Li-chung Chang
  • Patent number: 7696828
    Abstract: A modified derivative superposition (MDS) low noise amplifier (LNA) includes a main current path and a cancel current path. Third-order distortion in the cancel path is used to cancel third-order distortion in the main path. In one novel aspect, there is a separate source degeneration inductor for each of the two current paths, thereby facilitating tuning of one current path without affecting the other current path. In a second novel aspect, a deboost current path is provided that does not pass through the LNA load. The deboost current allows negative feedback to be increased without generating headroom problems. In a third novel aspect, the cancel current path and/or deboost current path is programmably disabled to reduce power consumption and improve noise figure in operational modes that do not require high linearity.
    Type: Grant
    Filed: January 4, 2008
    Date of Patent: April 13, 2010
    Assignee: QUALCOMM, Incorporated
    Inventor: Li-Chung Chang
  • Publication number: 20090258624
    Abstract: A receiver includes a jammer detector configured to detect the presence or the absence of jamming in a communication signal within a gain state. The receiver further includes an amplifier configured to amplify the communication signal in a high linearity receiving mode or a low linearity receiving mode, wherein the high linearity receiving mode corresponds with a lower gain for the gain state in the amplifier relative to that of the low linearity receiving mode. In addition, the receiver includes a processing unit coupled to the jammer detector, the processing unit being configured to control the amplifier to amplify the communication signal in either the high linearity receiving mode or the low linearity receiving mode, based on the output of the jammer detector detecting the presence or the absence of jamming in the communication signal. A method is also provided for processing a communication signal in a receiver.
    Type: Application
    Filed: September 18, 2008
    Publication date: October 15, 2009
    Applicant: QUALCOMM INCORPORATED
    Inventors: Prasad S. Gudem, Jose Cabanillas, Li-Chung Chang, Li Liu
  • Publication number: 20090174481
    Abstract: A modified derivative superposition (MDS) low noise amplifier (LNA) includes a main current path and a cancel current path. Third-order distortion in the cancel path is used to cancel third-order distortion in the main path. In one novel aspect, there is a separate source degeneration inductor for each of the two current paths, thereby facilitating tuning of one current path without affecting the other current path. In a second novel aspect, a deboost current path is provided that does not pass through the LNA load. The deboost current allows negative feedback to be increased without generating headroom problems. In a third novel aspect, the cancel current path and/or deboost current path is programmably disabled to reduce power consumption and improve noise figure in operational modes that do not require high linearity.
    Type: Application
    Filed: January 4, 2008
    Publication date: July 9, 2009
    Applicant: QUALCOMM INCORPORATED
    Inventor: Li-Chung Chang
  • Publication number: 20080234403
    Abstract: The present invention relates to a radiation curable and developable polyurethane which is characterized by having a carboxy group in its main chain and a acryloyl group in its side chain and comprising the following repeat units (I), (II), and (II) in a random arrangement: wherein R1, R2, R3, R4, and T are defined in the specification. The polyurethane has a weight molecular weight measured by GPC in a range of from 3,000 to 400,000; an acid value in a range of from 5 to 120 mgKOH/g. The present invention also relates to a radiation curable and developable composition containing the polyurethane.
    Type: Application
    Filed: March 20, 2008
    Publication date: September 25, 2008
    Inventors: Wei Hsiang Huang, Ying Jen Chen, Jui Ming Chang, Chun Hung Kuo, Hong Ye Lin, Li Chung Chang
  • Publication number: 20080227409
    Abstract: This disclosure describes techniques for reducing adverse effects of TX signal leakage in a full-duplex, wireless communication device. The techniques make use of a notch filter to reject TX signal leakage in a signal processed in the RX path of the wireless communication device. The notch filter may be constructed as a complex notch filter using passive resistor and capacitor components to produce a notch frequency that attenuates TX signal leakage components in a desired signal. The notch filter may be applied to a down-converted, baseband signal produced by a passive mixer.
    Type: Application
    Filed: July 12, 2007
    Publication date: September 18, 2008
    Applicant: QUALCOMM INCORPORATED
    Inventors: Li-Chung Chang, Prasad S. Gudem, Jose Cabanillas
  • Patent number: 7323369
    Abstract: Scan lines are formed on a substrate. A patterned dielectric layer and a patterned semiconductor layer are formed to cover portions of the scan lines. A patterned transparent conductive layer and a patterned metal layer are sequentially formed to define data lines, source/drain electrodes, pixel electrodes and etching protecting layers. The etching protective layers cover the exposed scan lines exposed by the patterned dielectric layer and the patterned semiconductor layer, and are electrically connected to the scan lines. A passivation layer is formed, and then the passivation layer over the pixel electrodes and the patterned metal layer of the pixel electrodes are removed to expose the patterned transparent conductive layer. The patterned semiconductor layer over the scan lines between the etching protective layers and the data lines is removed to expose the patterned dielectric layer over the scan lines.
    Type: Grant
    Filed: December 25, 2006
    Date of Patent: January 29, 2008
    Assignee: Au Optronics Corporation
    Inventors: Chia-Tsung Lee, Yu-Rung Huang, Li-Chung Chang, Chia-Hui Chueh