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).

  • Patent number: 10333469
    Abstract: An apparatus includes a first plurality of low noise amplifiers (LNAs) and a cascaded switch configured to route outputs of the first plurality of LNAs to a second plurality of LNAs.
    Type: Grant
    Filed: December 11, 2017
    Date of Patent: June 25, 2019
    Assignee: QUALCOMM Incorporated
    Inventors: Li-Chung Chang, Liang Dai, Prasad Srinivasa Siva Gudem
  • Publication number: 20190028087
    Abstract: A filter circuit may include a first path having a first complex baseband filter. The circuit may further include a second path having a second complex baseband filter. The circuit may further include a combiner coupled to an output of the first complex baseband filter and an output of the second complex baseband filter.
    Type: Application
    Filed: January 10, 2018
    Publication date: January 24, 2019
    Inventors: Wei ZHUO, Timothy Donald GATHMAN, Wenbang XU, Li-chung CHANG, Rui LI, Rahul KARMAKER
  • Patent number: 10008987
    Abstract: A low noise amplifier (LNA) reduces matching and switch noise. The LNA includes a main radio frequency signal path, an auxiliary radio frequency signal path and a phase shifter. The main path includes a first transistor and an inductor. The inductor is positioned between an input port of the LNA and the first transistor. The first transistor receives an input radio frequency signal via the inductor and provides a first amplified signal based on the input radio frequency signal. The auxiliary radio frequency signal path provides a second amplified signal for a noise cancellation mode based on the input radio frequency signal. The phase shifter applies a phase shift to an output signal of the LNA based on the first amplified signal and the second amplified signal.
    Type: Grant
    Filed: May 1, 2017
    Date of Patent: June 26, 2018
    Assignee: QUALCOMM Incorporated
    Inventors: Serkan Sayilir, Chuan Wang, Li-chung Chang, Kevin Hsi Huai Wang
  • Publication number: 20180175806
    Abstract: A low noise amplifier may include a post distortion cancellation block coupled to the low noise amplifier. The post distortion cancellation block may include a diode, and phase-shift logic. The phase-shift logic may be coupled in series with the diode.
    Type: Application
    Filed: May 1, 2017
    Publication date: June 21, 2018
    Inventors: Mohammad Sadegh MEHRJOO, Chuan WANG, Yanming XIAO, Li-chung CHANG, Kevin Hsi Huai WANG
  • Publication number: 20180175805
    Abstract: A low noise amplifier (LNA) reduces matching and switch noise. The LNA includes a main radio frequency signal path, an auxiliary radio frequency signal path and a phase shifter. The main path includes a first transistor and an inductor. The inductor is positioned between an input port of the LNA and the first transistor. The first transistor receives an input radio frequency signal via the inductor and provides a first amplified signal based on the input radio frequency signal. The auxiliary radio frequency signal path provides a second amplified signal for a noise cancellation mode based on the input radio frequency signal. The phase shifter applies a phase shift to an output signal of the LNA based on the first amplified signal and the second amplified signal.
    Type: Application
    Filed: May 1, 2017
    Publication date: June 21, 2018
    Inventors: Serkan SAYILIR, Chuan WANG, Li-chung CHANG, Kevin Hsi Huai WANG
  • Publication number: 20180102740
    Abstract: An apparatus includes a first plurality of low noise amplifiers (LNAs) and a cascaded switch configured to route outputs of the first plurality of LNAs to a second plurality of LNAs.
    Type: Application
    Filed: December 11, 2017
    Publication date: April 12, 2018
    Inventors: Li-Chung Chang, Liang Dai, Prasad Srinivasa Siva Gudem
  • Patent number: 9843291
    Abstract: An apparatus includes a first plurality of low noise amplifiers (LNAs) and a cascaded switch configured to route outputs of the first plurality of LNAs to a second plurality of LNAs.
    Type: Grant
    Filed: August 7, 2015
    Date of Patent: December 12, 2017
    Assignee: QUALCOMM Incorporated
    Inventors: Li-Chung Chang, Liang Dai, Prasad Srinivasa Siva Gudem
  • Patent number: 9837968
    Abstract: Amplifiers with noise splitting to improve noise figure are disclosed. In an exemplary design, an apparatus (e.g., a wireless device, an integrated circuit, etc.) includes a plurality of amplifier circuits and at least one interconnection circuit. The amplifier circuits receive an input radio frequency (RF) signal. The interconnection circuit(s) are coupled between the plurality of amplifier circuits. Each interconnection circuit is closed to short the outputs or internal nodes of two amplifier circuits coupled to that interconnection circuit. The plurality of amplifier circuits may include a plurality of gain circuits coupled to a plurality of current buffers, one gain circuit and one current buffer for each amplifier circuit. Each amplifier circuit provides an output current, which may include a portion of the current from each of the plurality of gain circuits when the plurality of amplifier circuits are enabled.
    Type: Grant
    Filed: December 12, 2016
    Date of Patent: December 5, 2017
    Assignee: QUALCOMM Incorporated
    Inventors: Rui Xu, Li-Chung Chang
  • Patent number: 9723560
    Abstract: An apparatus includes a first amplifier stage configured to amplify a first carrier signal. The apparatus includes a second amplifier stage configured to amplify a second carrier signal. A resistive-capacitive (RC) network is coupled to the first amplifier stage and to the second amplifier stage. The RC network includes a resistive element coupled to a capacitive element.
    Type: Grant
    Filed: March 4, 2015
    Date of Patent: August 1, 2017
    Assignee: QUALCOMM Incorporated
    Inventors: Ahmed Abdel Monem Youssef, Wingching Vincent Leung, Rui Xu, Udara Charman Fernando, Ketan Humnabadkar, Tsai-Chen Huang, Li-Chung Chang
  • Patent number: 9692470
    Abstract: An apparatus includes a low noise amplifier (LNA) having an input configured to receive a radio frequency signal. The apparatus also includes a notch filter coupled to an input of the LNA. The notch filter is configured to attenuate the radio frequency signal at a notch frequency.
    Type: Grant
    Filed: August 25, 2015
    Date of Patent: June 27, 2017
    Assignee: QUALCOMM Incorporated
    Inventors: Hajir Hedayati, Milad Darvishi, Li-Chung Chang
  • Patent number: 9642166
    Abstract: An apparatus includes a first amplifier circuit and a second amplifier circuit. The first amplifier circuit has a first output coupled to a first load circuit in a multi-output mode, and the second amplifier circuit has a second output coupled to a second load circuit in the multi-output mode. The apparatus further includes a first divert circuit and a second divert circuit. The first divert circuit is configured to divert a first portion of a first amplified signal from the first amplifier circuit to the second load circuit in the multi-output mode. The second divert circuit is configured to divert a first portion of a second amplified signal from the second amplifier circuit to the first load circuit in the multi-output mode.
    Type: Grant
    Filed: March 10, 2015
    Date of Patent: May 2, 2017
    Assignee: Qualcomm Incorporated
    Inventors: Sang Hyun Woo, Wingching Vincent Leung, Li-Chung Chang
  • Publication number: 20170093343
    Abstract: Amplifiers with noise splitting to improve noise figure are disclosed. In an exemplary design, an apparatus (e.g., a wireless device, an integrated circuit, etc.) includes a plurality of amplifier circuits and at least one interconnection circuit. The amplifier circuits receive an input radio frequency (RF) signal. The interconnection circuit(s) are coupled between the plurality of amplifier circuits. Each interconnection circuit is closed to short the outputs or internal nodes of two amplifier circuits coupled to that interconnection circuit. The plurality of amplifier circuits may include a plurality of gain circuits coupled to a plurality of current buffers, one gain circuit and one current buffer for each amplifier circuit. Each amplifier circuit provides an output current, which may include a portion of the current from each of the plurality of gain circuits when the plurality of amplifier circuits are enabled.
    Type: Application
    Filed: December 12, 2016
    Publication date: March 30, 2017
    Inventors: Rui Xu, Li-Chung Chang
  • Patent number: 9608437
    Abstract: Techniques for improving electro-static discharge (ESD) performance in integrated circuits (IC's). In an aspect, one or more protective diodes are provided between various nodes of the IC. For example, protective diode(s) may be provided between the drain and gate of an amplifier input transistor, and/or between the drain and ground, etc. In certain exemplary embodiments, the amplifier may be a cascode amplifier. Further aspects for effectively dealing with ESD phenomena are described.
    Type: Grant
    Filed: September 12, 2013
    Date of Patent: March 28, 2017
    Assignee: Qualcomm Incorporated
    Inventors: Ahmed Abdel Monem Youssef, Prasad Srinivasa Siva Gudem, Li-Chung Chang, Ehab Ahmed Sobhy Abdel Ghany
  • Publication number: 20170063414
    Abstract: An apparatus includes a low noise amplifier (LNA) having an input configured to receive a radio frequency signal. The apparatus also includes a notch filter coupled to an input of the LNA. The notch filter is configured to attenuate the radio frequency signal at a notch frequency.
    Type: Application
    Filed: August 25, 2015
    Publication date: March 2, 2017
    Inventors: Hajir Hedayati, Milad Darvishi, Li-Chung Chang
  • Publication number: 20170040947
    Abstract: An apparatus includes a first plurality of low noise amplifiers (LNAs) and a cascaded switch configured to route outputs of the first plurality of LNAs to a second plurality of LNAs.
    Type: Application
    Filed: August 7, 2015
    Publication date: February 9, 2017
    Inventors: Li-Chung Chang, Liang Dai, Prasad Srinivasa Siva Gudem
  • Patent number: 9559640
    Abstract: A CMOS amplifier including electrostatic discharge (ESD) protection circuits is disclosed. In one embodiment, the CMOS amplifier may include a PMOS transistor, a NMOS transistor, primary protection diodes, and one or more auxiliary protection diodes to limit a voltage difference between terminals of the CMOS amplifier. In some embodiments, the auxiliary protection diodes may limit the voltage difference between an input terminal of the CMOS amplifier and a supply voltage, the input terminal of the CMOS amplifier and ground, and the input terminal and the output terminal of the CMOS amplifier.
    Type: Grant
    Filed: February 26, 2015
    Date of Patent: January 31, 2017
    Assignee: QUALCOMM Incorporated
    Inventors: Ahmed Abdel Monem Youssef, Prasad Srinivasa Siva Gudem, Eugene Robert Worley, Dongling Pan, Li-Chung Chang
  • Patent number: 9543903
    Abstract: Amplifiers with noise splitting to improve noise figure are disclosed. In an exemplary design, an apparatus (e.g., a wireless device, an integrated circuit, etc.) includes a plurality of amplifier circuits and at least one interconnection circuit. The amplifier circuits receive an input radio frequency (RF) signal. The interconnection circuit(s) are coupled between the plurality of amplifier circuits. Each interconnection circuit is closed to short the outputs or internal nodes of two amplifier circuits coupled to that interconnection circuit. The plurality of amplifier circuits may include a plurality of gain circuits coupled to a plurality of current buffers, one gain circuit and one current buffer for each amplifier circuit. Each amplifier circuit provides an output current, which may include a portion of the current from each of the plurality of gain circuits when the plurality of amplifier circuits are enabled.
    Type: Grant
    Filed: October 22, 2012
    Date of Patent: January 10, 2017
    Assignee: QUALCOMM Incorporated
    Inventors: Rui Xu, Li-Chung Chang
  • Patent number: 9496883
    Abstract: A calibration method includes generating, by a digital-to-analog converter of a chip, a first predetermined voltage and a second predetermined voltage and outputting the same to an analog-to-digital-converter of the chip to generate a first digital code difference; determining a variation parameter according to the first digital code difference and one of a plurality of second digital code differences stored in a look up table of a memory unit of the chip; driving, by an external testing system, the digital-to-analog converter to generate the first predetermined voltage and the second predetermined voltage and output the same to the analog-to-digital-converter to generate a target code difference; and multiplying the second digital code differences with the variation parameter to calibrate a gain of the analog-to-digital converter according to the target code difference.
    Type: Grant
    Filed: May 19, 2016
    Date of Patent: November 15, 2016
    Assignee: Realtek Semiconductor Corporation
    Inventors: Li-Chung Chang, Chi-Hsuan Kuan
  • Patent number: 9479131
    Abstract: An apparatus includes a first amplification stage configured to amplify a first carrier signal and a second amplification stage configured to amplify a second carrier signal. The first amplification stage is direct-current (DC) coupled to the second amplification stage. First circuitry is coupled to the first amplification stage and configured to control a first gain of the first amplification stage. The first circuitry includes a first gain control transistor configured to selectively divert a first bleed current from a first output of the first amplification stage. Second circuitry is coupled to the second amplification stage and configured to control a second gain of the second amplification stage independently of the first gain. The second circuitry includes a second gain control transistor configured to selectively divert a second bleed current from a second output of the second amplification stage.
    Type: Grant
    Filed: March 10, 2015
    Date of Patent: October 25, 2016
    Assignee: Qualcomm Incorporated
    Inventors: Ahmed Abdel Monem Youssef, Ehab Ahmed Sobhy Abdel Ghany, Li-Chung Chang
  • Patent number: 9467104
    Abstract: A device includes at least one first amplifier circuit configurable to receive and amplify an input radio frequency (RF) signal having a first carrier at a first input signal level and provide a first amplified RF signal, and at least one second amplifier circuit configurable to receive and amplify the input RF signal having a second carrier at a second input signal level and provide a second amplified RF signal, the at least one first amplifier circuit having a first input impedance, the at least one second amplifier circuit having a second input impedance.
    Type: Grant
    Filed: March 28, 2014
    Date of Patent: October 11, 2016
    Assignee: Qualcomm Incorporated
    Inventors: Rui Xu, Allen He, Wingching Vincent Leung, Ahmed Abdel Monem Youssef, Ehab Ahmed Sobhy Abdel Ghany, Sang Hyun Woo, Li-Chung Chang