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).
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Publication number: 20140072001Abstract: 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: ApplicationFiled: September 11, 2012Publication date: March 13, 2014Applicant: QUALCOMM INCORPORATEDInventors: Li-Chung Chang, Prasad Srinivasa Siva Gudem, Frederic Bossu, Christian Holenstein
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Publication number: 20130231064Abstract: 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: ApplicationFiled: March 2, 2012Publication date: September 5, 2013Applicant: QUALCOMM INCORPORATEDInventors: Prasad Srinivasa Siva Gudem, Gurkanwal Singh Sahota, Li-Chung Chang, Christian Holenstein, Frederic Bossu
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Publication number: 20130230080Abstract: 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: ApplicationFiled: March 2, 2012Publication date: September 5, 2013Applicant: QUALCOMM INCORPORATEDInventors: Prasad Srinivasa Siva Gudem, Xiaoyin He, Tamer Adel Kadous, Li-Chung Chang
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Patent number: 8526903Abstract: 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: GrantFiled: March 11, 2008Date of Patent: September 3, 2013Assignee: QUALCOMM, IncorporatedInventors: Prasad S Gudem, Li-Chung Chang
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Publication number: 20130226496Abstract: 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: ApplicationFiled: February 29, 2012Publication date: August 29, 2013Applicant: QUALCOMM IncorporatedInventors: Prasad S. Gudem, Bhushan Shanti Asuri, Li-Chung Chang, Vinod V. Panikkath
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Patent number: 8433272Abstract: 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: GrantFiled: September 18, 2008Date of Patent: April 30, 2013Assignee: Qualcomm IncorporatedInventors: Prasad S. Gudem, Jose Cabanillas, Li-Chung Chang, Li Liu
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Publication number: 20130003617Abstract: 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: ApplicationFiled: June 29, 2011Publication date: January 3, 2013Applicant: QUALCOMM IncorporatedInventors: Prasad Srinivasa Siva Gudem, Tamer Adel Kadous, Sumit Verma, Li-chung Chang
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Publication number: 20120327825Abstract: 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: ApplicationFiled: March 2, 2012Publication date: December 27, 2012Applicant: QUALCOMM INCORPORATEDInventors: Prasad Srinivasa Siva Gudem, Udara C. Fernando, Li-Chung Chang
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Patent number: 8310312Abstract: 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: GrantFiled: August 11, 2009Date of Patent: November 13, 2012Assignee: QUALCOMM, IncorporatedInventors: Hanil Lee, Li-Chung Chang
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Patent number: 8270499Abstract: 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: GrantFiled: May 15, 2009Date of Patent: September 18, 2012Assignee: QUALCOMM, IncorporatedInventors: Li-Chung Chang, Maulin P. Bhagat, Hanil Lee, Ravi Sridhara
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Patent number: 8036623Abstract: 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: GrantFiled: July 12, 2007Date of Patent: October 11, 2011Assignee: QUALCOMM, IncorporatedInventors: Li-Chung Chang, Prasad S. Gudem, Jose Cabanillas
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Publication number: 20110110463Abstract: 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: ApplicationFiled: May 15, 2009Publication date: May 12, 2011Applicant: QUALCOMM INCORPORATEDInventors: Li-Chung Chang, Maulin P. Bhagat, Hanil Lee, Ravi Sridhara
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Patent number: 7935776Abstract: 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: GrantFiled: March 20, 2008Date of Patent: May 3, 2011Assignee: AGI CorporationInventors: Wei Hsiang Huang, Ying Jen Chen, Jui Ming Chang, Chun Hung Kuo, Hong Ye Lin, Li Chung Chang
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Publication number: 20110037518Abstract: 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: ApplicationFiled: August 11, 2009Publication date: February 17, 2011Applicant: QUALCOMM INCORPORATEDInventors: Hanil Lee, Li-chung Chang
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Patent number: 7696828Abstract: 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: GrantFiled: January 4, 2008Date of Patent: April 13, 2010Assignee: QUALCOMM, IncorporatedInventor: Li-Chung Chang
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Publication number: 20090258624Abstract: 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: ApplicationFiled: September 18, 2008Publication date: October 15, 2009Applicant: QUALCOMM INCORPORATEDInventors: Prasad S. Gudem, Jose Cabanillas, Li-Chung Chang, Li Liu
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Publication number: 20090174481Abstract: 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: ApplicationFiled: January 4, 2008Publication date: July 9, 2009Applicant: QUALCOMM INCORPORATEDInventor: Li-Chung Chang
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Publication number: 20080234403Abstract: 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: ApplicationFiled: March 20, 2008Publication date: September 25, 2008Inventors: Wei Hsiang Huang, Ying Jen Chen, Jui Ming Chang, Chun Hung Kuo, Hong Ye Lin, Li Chung Chang
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Publication number: 20080227409Abstract: 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: ApplicationFiled: July 12, 2007Publication date: September 18, 2008Applicant: QUALCOMM INCORPORATEDInventors: Li-Chung Chang, Prasad S. Gudem, Jose Cabanillas
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Patent number: 7323369Abstract: 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: GrantFiled: December 25, 2006Date of Patent: January 29, 2008Assignee: Au Optronics CorporationInventors: Chia-Tsung Lee, Yu-Rung Huang, Li-Chung Chang, Chia-Hui Chueh