Patents by Inventor Ligang Zhang

Ligang Zhang 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: 20100124883
    Abstract: Systems and methods are disclosed for an integrated air loop antenna and transformer antenna assembly that provides improved performance in receiving RF signals and AM broadcast channels, in particular. In one embodiment, an air loop antenna is coupled to a transformer to form an integrated antenna assembly. This integrated air loop antenna and transformer antenna assembly can then be connected to a radio device having antenna connections.
    Type: Application
    Filed: November 17, 2008
    Publication date: May 20, 2010
    Inventors: Zhiqi Hu, Ligang Zhang, Chengzhou Lin
  • Publication number: 20090253391
    Abstract: Systems and methods are disclosed that use multiple DC-DC (direct-current-to-direct-current) regulators and configurable DC-DC regulators with respect to multi-band audio receivers in order to allow for the use of different DC-DC regulator switching clock signals for different audio broadcast bands. The systems and methods disclosed thereby help to alleviate interference problems typically caused by switching devices used in the DC-DC conversion process. The embodiments described are also applicable to switching power supplies run from alternating current (AC) power sources and to Class D amplifiers working with broadcast radios.
    Type: Application
    Filed: September 30, 2008
    Publication date: October 8, 2009
    Inventor: Ligang Zhang
  • Publication number: 20090247101
    Abstract: Methods and systems are disclosed for automatic detection of channel spacing for broadcast bands in different regions that use different channel spacing. Using the described embodiments, channel spacing at a users' current location can be automatically detected so that manual settings by the user are not necessary, especially when a user travels with his/her radio across regions that use different channel spacing for radio broadcasting bands. This auto-detected channel spacing can then be used for later channel searching by the radio. More particularly, methods and systems are disclosed for auto-detection of channel spacing for AM broadcasts using different channel spacings, such as the standard 9 kHz and 10 kHz spacings, used today in different geographic regions of the world for AM broadcast bands.
    Type: Application
    Filed: September 30, 2008
    Publication date: October 1, 2009
    Inventors: Ligang Zhang, Steve W. Hanawalt, Greg Hodgson, Liang Wu
  • Patent number: 7561865
    Abstract: A communications device including communications circuitry, tunable filter circuitry including a node configured to pass a signal between an antenna and the communication circuitry, and control circuitry configured to cause energy in the tunable filter circuitry to be adjusted for a time period and configured to determine a resonant frequency of the tunable filter circuitry from oscillations on the node caused by the energy subsequent to the time period is provided.
    Type: Grant
    Filed: September 29, 2006
    Date of Patent: July 14, 2009
    Assignee: Silicon Laboratories, Inc.
    Inventors: Ligang Zhang, Scott D. Willingham, Peter J. Vancorenland, Yunteng Huang
  • Patent number: 7522690
    Abstract: Jitter is measured by receiving a first reference signal at a first phase-locked loop (PLL) circuit and generating at an output of the first phase-locked loop circuit an output signal based at least in part on the first reference signal, the output signal including a jitter component to be measured. A signal corresponding to the output signal and a signal corresponding to the first reference signal are compared in a phase detector of a second phase-locked loop circuit. A value corresponding to an output of the comparison is stored that includes information indicative of the measured jitter component.
    Type: Grant
    Filed: December 6, 2004
    Date of Patent: April 21, 2009
    Assignee: Silicon Laboratories Inc.
    Inventor: Ligang Zhang
  • Patent number: 7501924
    Abstract: An oscillator circuit formed at least partially on an integrated circuit substrate includes a self-shielding inductor. The self-shielding inductor has a toroidal structure. A coil forms a structure that is symmetric around an axis orthogonal to a surface of the integrated circuit substrate. A magnetic filed generated by the self-shielding inductor is confined to a core region of the coil. Portions of the self-shielding inductor may be formed in integrated circuit layers, redistribution layers, package layers, through-substrate interconnect, backside substrate conductor layers, or combinations thereof.
    Type: Grant
    Filed: September 30, 2005
    Date of Patent: March 10, 2009
    Assignee: Silicon Laboratories Inc.
    Inventor: Ligang Zhang
  • Patent number: 7498656
    Abstract: An improved electromagnetic shielding structure has been discovered. In one embodiment of the invention, an apparatus includes an inductor and an electrically conductive enclosure that electromagnetically shields the inductor. The electrically conductive enclosure has an aperture at least as large as the inductor. The aperture is substantially centered around a projected surface of the inductor. The apparatus may include one or more electrically conductive links extending across the aperture and electrically coupled to the electrically conductive enclosure. The electrically conductive links reduce an effect of electromagnetic signals external to the electrically conductive enclosure on the inductor.
    Type: Grant
    Filed: March 31, 2004
    Date of Patent: March 3, 2009
    Assignee: Silicon Laboratories Inc.
    Inventors: Ligang Zhang, David Pietruszynski, Axel Thomsen, Kevin G. Smith
  • Publication number: 20080211588
    Abstract: A noise cancellation signal is generated for a fractional-N phase-locked loop (200). A divide value is provided to a first delta sigma modulator circuit (203), which generates a divide control signal to control a divide value of a feedback divider (208) in the phase-locked loop. An error term (e) is generated that is indicative of a difference between the generated divide control signal and the divide value supplied to the first delta sigma modulator circuit. The error term is integrated in an integrator (320) to generate an integrated error term (x), where xk+1=xk+ek; and a phase error correction circuit (209) utilizes the error term ek and the integrated error term xk to generate the phase error cancellation signal.
    Type: Application
    Filed: June 28, 2005
    Publication date: September 4, 2008
    Inventors: Douglas R. Frey, Axel Thomsen, Ligang Zhang
  • Patent number: 7375411
    Abstract: A region of high metal density may be placed in metal layers proximate to an area of low metal density below an inductor on an integrated circuit without violating manufacturing design rules for reducing manufacturing defects and without substantially impacting performance of the inductor. These results are achieved by including a transitional region that includes conductive structures electrically isolated from each other between the region of high metal density and the region of low metal density. The transitional region has a structure that allows a negligible amount of current flow to be induced in the structure.
    Type: Grant
    Filed: June 3, 2004
    Date of Patent: May 20, 2008
    Assignee: Silicon Laboratories Inc.
    Inventor: Ligang Zhang
  • Patent number: 7365610
    Abstract: The effect of supply voltage variations on an oscillator circuit output are compensated for to reduce supply pushing. The change in a value of a first capacitance in a first direction in response to the variation in the supply voltage is canceled using one or more diodes having a capacitance that changes in a second direction, opposite the first direction, in response to the variation in the supply voltage.
    Type: Grant
    Filed: March 21, 2005
    Date of Patent: April 29, 2008
    Assignee: Silicon Laboratories Inc.
    Inventor: Ligang Zhang
  • Publication number: 20080081583
    Abstract: A communications device including communications circuitry, tunable filter circuitry including a node configured to pass a signal between an antenna and the communication circuitry, and control circuitry configured to cause energy in the tunable filter circuitry to be adjusted for a time period and configured to determine a resonant frequency of the tunable filter circuitry from oscillations on the node caused by the energy subsequent to the time period is provided.
    Type: Application
    Filed: September 29, 2006
    Publication date: April 3, 2008
    Inventors: Ligang Zhang, Scott D. Willingham, Peter J. Vancorenland, Yunteng Huang
  • Patent number: 7348818
    Abstract: A locking range of a current mode logic (CML) frequency divider circuit is tunable by dynamically adjusting a tail current of the frequency divider circuit according to a control signal. The control signal may be based on at least one control signal coupled to tune a controllable oscillator. The control signal may be based on a frequency of an output of a voltage controlled oscillator coupled to the frequency divider. The control signal may be based on the voltage swing of an output of a voltage controlled oscillator coupled to the frequency divider. The control signal may be based on an output of the frequency divider circuit.
    Type: Grant
    Filed: June 30, 2005
    Date of Patent: March 25, 2008
    Assignee: Silicon Laboratories Inc.
    Inventors: Ronald B. Hulfachor, Ligang Zhang
  • Patent number: 7310039
    Abstract: It has been discovered that an inductor may be made to include a surface rotational portion instead of a coil to provide a low inductance inductor with sufficient quality factor. The surface rotational portion is a conducting structure which is substantially enclosed along the length of the structure and which has openings at each end of the structure and an opening along the length of the structure between the end openings. One example of such a structure is a cylinder having a lateral opening and openings at its ends or bases. Another example of such a structure is a duct-shape or rectangular structure. Any appropriately shaped surface may be used to rotate current, and varying thicknesses and lengths may be used as appropriate.
    Type: Grant
    Filed: November 30, 2001
    Date of Patent: December 18, 2007
    Assignee: Silicon Laboratories Inc.
    Inventor: Ligang Zhang
  • Publication number: 20070246805
    Abstract: A technique for improving the quality factor of an inductor includes increasing a cross-sectional area of the inductor by increasing a vertical dimension associated with the inductor. An apparatus includes an inductor formed partially in a first integrated circuit die and formed partially in at least a second integrated circuit die. The inductor may be formed partially in at least one interconnect structure between the first integrated circuit die and the second integrated circuit die. In at least one embodiment of the invention, the inductor is self-shielding and is configured to generate a magnetic field in response to a current flowing through coupled conductor portions of the self-shielding inductor. The magnetic field of the self-shielding inductor is substantially confined to a core region of the self-shielding inductor.
    Type: Application
    Filed: June 29, 2006
    Publication date: October 25, 2007
    Inventors: Ligang Zhang, John M. Czarnowski
  • Patent number: 7253693
    Abstract: A variable capacitance circuit includes a first and a second capacitor. A switch having an associated first nonlinear capacitance, selectively couples the first and second capacitors. To compensate for the first nonlinear capacitance, a second nonlinear capacitance is coupled to the switch that has a capacitance value responsive to a change in voltage that moves in a direction of change opposite to a direction of change of the first nonlinear capacitance.
    Type: Grant
    Filed: December 3, 2004
    Date of Patent: August 7, 2007
    Assignee: Silicon Laboratories Inc.
    Inventors: Ligang Zhang, Yunteng Huang
  • Patent number: 7236024
    Abstract: A PLL function may be implemented as a dual-loop structure having a first PLL circuit which generates an intermediate signal from the reference signal, and a second PLL circuit which generates an output signal from the intermediate signal. The intermediate signal frequency is preferably chosen at a value in which potential interference signals do not have much energy. The first loop preferably has low bandwidth to provide good input jitter attenuation, while second loop preferably has higher bandwidth to reduce phase noise of the output signal. The circuit preferably provides for a choice of several different intermediate frequencies to allow use where different intermediate frequencies may exist in each system. Moreover, in a system having two such dual-loop PLL circuits, each can be configured with a different intermediate frequency, so that interference from one to the other is reduced.
    Type: Grant
    Filed: September 30, 2005
    Date of Patent: June 26, 2007
    Assignee: Silicon Laboratories Inc.
    Inventors: Yunteng Huang, Ligang Zhang, Axel Thomsen
  • Publication number: 20070089609
    Abstract: The invention relates to an oil-gas-water multi-phase flow adjusting apparatus, which mainly comprises an inlet accelerating pipe section, a vortex flow guide spiral pipe, a gas circuit exit connection pipe section, a liquid receiving cone, a mixed liquid relief exit connection pipe section and a sampler exit connection pipe section, and which has the function for changing at intervals the flow pattern, the flow state and the components of the oil-gas-water multi-phase flow. The invention also relates to an oil-gas-water multi-phase flow rate measuring apparatus and its measuring method. The measuring apparatus comprises a blind three-way mixing means, a pressure differential type flow measuring device, a single-? phase volume fraction meter, a dual-? phase volume fraction meter, an oil-gas-water multi-phase flow adjusting apparatus and a computing system.
    Type: Application
    Filed: May 16, 2003
    Publication date: April 26, 2007
    Applicant: Haimo Technologies, Inc.
    Inventors: Jianwen Dou, Jinsong Wan, Ligang Zhang
  • Publication number: 20070084340
    Abstract: An adjustable type guide vortex gas-liquid separating apparatus is provided, it comprises a case, a vortex flow guide spiral pipe, a mist eliminator, an adjusting valve and a ? ray phase volume fraction meter. Its separating method is to make the oil-gas-water multiphase flow move in vortex, and thus to realize the gas-liquid separation, then to measure the gas content of the separated liquid phase by using the ? ray phase volume fraction meter and to send out control information as judged by the magnitude of the gas content in the liquid phase, so as to control the opening of the adjusting valve of the gas circuit, thus to achieve adjustment of the gas-liquid separation effects, and to control the gas content of the liquid phase to a certain range.
    Type: Application
    Filed: May 16, 2003
    Publication date: April 19, 2007
    Inventors: Jianwen Dou, Jinsong Wan, Ligang Zhang
  • Publication number: 20070075813
    Abstract: An oscillator circuit formed at least partially on an integrated circuit substrate includes a self-shielding inductor. The self-shielding inductor has a toroidal structure. A coil forms a structure that is symmetric around an axis orthogonal to a surface of the integrated circuit substrate. A magnetic filed generated by the self-shielding inductor is confined to a core region of the coil. Portions of the self-shielding inductor may be formed in integrated circuit layers, redistribution layers, package layers, through-substrate interconnect, backside substrate conductor layers, or combinations thereof.
    Type: Application
    Filed: September 30, 2005
    Publication date: April 5, 2007
    Inventor: Ligang Zhang
  • Publication number: 20070001719
    Abstract: A locking range of a current mode logic (CML) frequency divider circuit is tunable by dynamically adjusting a tail current of the frequency divider circuit according to a control signal. The control signal may be based on at least one control signal coupled to tune a controllable oscillator. The control signal may be based on a frequency of an output of a voltage controlled oscillator coupled to the frequency divider. The control signal may be based on the voltage swing of an output of a voltage controlled oscillator coupled to the frequency divider. The control signal may be based on an output of the frequency divider circuit.
    Type: Application
    Filed: June 30, 2005
    Publication date: January 4, 2007
    Inventors: Ron Hulfachor, Ligang Zhang