With Balancing Or Neutralizing Patents (Class 455/305)
  • Patent number: 8977224
    Abstract: A transceiver for radio-frequency identification (RFID) is provided. The transceiver includes a transmitter, a receiver and a noise canceller. The transmitter transmits a carrier signal to an antenna. The receiver receives a wireless signal from the antenna. The noise canceller generates a feedback current according to a part of the carrier signal, and feeds the feedback current to an input of the receiver to cancel noises in the wireless signal. Further, the noise canceller adjusts the feedback current according to the signal strength of the noises in the wireless signal.
    Type: Grant
    Filed: August 9, 2012
    Date of Patent: March 10, 2015
    Assignee: MStar Semiconductor, Inc.
    Inventor: Shou-Fang Chen
  • Patent number: 8942655
    Abstract: An integrated circuit comprising processing logic for operably coupling to radio frequency (RF) receiver circuitry arranged to receive a wireless network signal. The receiver circuitry generates in-phase and quadrature digital baseband representations of the wireless network signal. The processing logic determines quadrature (I/Q) imbalance of the RF receiver circuitry based on the in-phase and quadrature digital baseband representations of the wireless network signal.
    Type: Grant
    Filed: May 31, 2007
    Date of Patent: January 27, 2015
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Norman Beamish, Conor O'Keeffe, Patrick Pratt
  • Patent number: 8929847
    Abstract: A signal processing circuit with noise cancellation includes an impedance matching unit and a transconductance stage. The impedance matching unit is disposed at a first path, and arranged to provide input impedance matching, wherein the impedance matching unit is a passive element, and the first path is coupled between a signal input port and a signal output port. The transconductance stage is disposed at a second path, and arranged to guide circuit introduced noise to the signal output port for noise cancellation at the signal output port, wherein the second path is coupled between the signal input port and the signal output port.
    Type: Grant
    Filed: April 22, 2014
    Date of Patent: January 6, 2015
    Assignee: Mediatek Inc.
    Inventors: Yuan-Hung Chung, Yi-Shing Shih
  • Patent number: 8885781
    Abstract: A system and method for detecting burst noise during quadrature amplitude modulation (QAM) communications are provided. A QAM signal is acquired at a receiver in communication with a network. The QAM signal is demodulated at the receiver to identify a plurality of symbols. Amplitudes for each of the plurality of symbols are determined, and are compared to a predetermined threshold. For each amplitude that is greater than the predetermined threshold, information is recorded at the receiver relating to a burst noise event. The magnitude of the burst noise can be determined by measuring a difference between a received constellation point and a perimeter constellation point closest to the received constellation point. The information about the burst noise event can be transmitted to an error correction module for reducing future burst noise in the network. Equalizer coefficients and tracking loop performance can be adjusted/enhanced using the burst noise information.
    Type: Grant
    Filed: November 6, 2012
    Date of Patent: November 11, 2014
    Assignee: Casa Systems, Inc.
    Inventor: David Fox
  • Patent number: 8855592
    Abstract: A method is disclosed for mitigating narrowband interference within a system for wideband communications. The method can include separating a wideband signal into a plurality of sub bands, detecting energy levels in the sub-bands, and activating a control signal if the energy levels of the sub-bands differ by a predetermined amount. Such a difference in energy levels can indicate that narrowband interference is present and interference mitigation features can be activated. In another embodiment, a system is disclosed that has a band splitter and a plurality of energy level detectors to detect energy differences in the sub bands. Other embodiments are also disclosed.
    Type: Grant
    Filed: May 27, 2008
    Date of Patent: October 7, 2014
    Assignee: Intel Corporation
    Inventors: Andrey V Belogolovy, Mikhail Lyakh, Alan E. Waltho, Anu Hannele Huttunen, Risto Kaunisto
  • Publication number: 20140287708
    Abstract: A circuit used in a mixer configured to receive a signal made up of a relatively small modulation signal and a relatively large carrier signal is described. The mixer includes multiple switches. A balancing circuit configured to receive a supply voltage and a clocking signal is provided, and the balancing circuit provides a control signal to a switch in the mixer. The balancing circuit includes a capacitor configured to receive and selectively dissipate charge as a gate voltage along a gate path. The control signal causes switching of the switch in the mixer at times in accordance with the clocking signal according to a voltage difference value between a source voltage and the gate voltage, wherein the voltage difference value between the source voltage and the gate voltage is approximately a predetermined voltage value greater than a turn on voltage level of the switch.
    Type: Application
    Filed: June 10, 2014
    Publication date: September 25, 2014
    Inventors: Haitao Gan, Xiaoyong Li
  • Patent number: 8768279
    Abstract: A first signal having a first polarization direction and a second signal having a second polarization direction crossing the first polarization direction are received. A phase of the second signal is controlled using a phase control signal. An interference compensation signal is generated by weighted combination on a time-series of a signal whose phase has been controlled. Weighting coefficients used for the weighted combination are set so that the interference compensation signal becomes a cross-polarization interference component of the first signal. A phase difference between the first signal and the second signal is estimated using the weighting coefficients. The phase control signal is generated using the estimated phase difference so that a phase of the first signal and the phase of the second signal become identical. The first signal is compensated for cross-polarization interference caused by the second signal using the interference compensation signal and the first signal.
    Type: Grant
    Filed: April 13, 2011
    Date of Patent: July 1, 2014
    Assignee: NEC Corporation
    Inventor: Yuuzou Suzuki
  • Patent number: 8750818
    Abstract: A signal processing circuit with noise cancellation includes an impedance matching unit and a transconductance stage. The impedance matching unit is disposed at a first path, and arranged to provide input impedance matching, wherein the impedance matching unit is a bilateral element, and the first path is coupled between a signal input port and a signal output port. The transconductance stage is disposed at a second path, and arranged to guide circuit introduced noise to the signal output port for noise cancellation at the signal output port, wherein the second path is coupled between the signal input port and the signal output port.
    Type: Grant
    Filed: March 11, 2013
    Date of Patent: June 10, 2014
    Assignee: Mediatek Inc.
    Inventors: Yuan-Hung Chung, Yi-Shing Shih
  • Patent number: 8724679
    Abstract: Transceiver calibration is a critical issue for proper transceiver operation. The transceiver comprises at least one RF transmit chain and one RF receive chain. A closed loop path is formed from the digital block, the RF transmit chain, the substrate coupling, the RF receive chain back to the digital block and is used to estimate and calibrate the transceiver parameters over the operating range of frequencies. The substrate coupling eliminates the need for the additional circuitry saving area, power, and performance. In place of the additional circuitry, the digital block which performs baseband operations can be reconfigured into a software or/and hardware mode to calibrate the transceiver. The digital block comprises a processor and memory and is coupled to the front end of the RF transmit chain and the tail end of the RF receive chain.
    Type: Grant
    Filed: April 9, 2012
    Date of Patent: May 13, 2014
    Assignee: Tensorcom, Inc.
    Inventor: Ismail Lakkis
  • Patent number: 8718584
    Abstract: A dual conversion receiver architecture that converts a radio frequency signal to produce a programmable intermediate frequency whose channel bandwidth and frequency can be changed using variable low-pass filtering to accommodate multiple standards for television and other wireless standards. The dual conversion receiver uses a two stage frequency translation and continual DC offset removal. The dual conversion receiver can be completely implemented on an integrated circuit with no external adjustments.
    Type: Grant
    Filed: July 6, 2010
    Date of Patent: May 6, 2014
    Assignee: MaxLinear, Inc.
    Inventors: Kishore Seendripu, Raymond Montemayor, Curtis Ling, Glenn Chang, Sheng Ye
  • Patent number: 8712361
    Abstract: A method for reciprocal-mixing noise cancellation may include receiving, from a first mixer, a first signal comprising a wanted signal at a first frequency and a modulated signal at a second frequency. The modulated signal may be a product of a reciprocal-mixing of an unwanted signal with a phase noise. The second frequency may be greater than the first frequency, and at least a portion of the modulated signal may overlap the wanted signal, adding a reciprocal-mixing noise to the wanted signal. Using the first signal, a narrow second signal may be generated at a third frequency, twice the second frequency. At a second mixer, the second signal may be mixed with the first signal to generate a third signal. The third signal may be subtracted from the first signal to remove a reciprocal-mixing noise and to generate the wanted signal at the first frequency without the reciprocal-mixing noise.
    Type: Grant
    Filed: November 21, 2012
    Date of Patent: April 29, 2014
    Assignee: Broadcom Corporation
    Inventors: Mohyee Mikhemar, David Murphy, Hooman Darabi
  • Patent number: 8666345
    Abstract: The invention relates to a filter (20) filtering a downlink signal of an antenna (13) of an indoor cellular system, the filter comprising a signal determining unit (24) determining a signal strength of an uplink signal received by said antenna (13), the filter adjusting a signal strength of the downlink signal of said antenna (13) in accordance with the signal strength of the uplink signal.
    Type: Grant
    Filed: April 9, 2009
    Date of Patent: March 4, 2014
    Assignee: Telefonaktiebolaget L M Ericsson (publ)
    Inventors: Said Soulhi, Taoufiq Abouzid
  • Patent number: 8611479
    Abstract: A communication system comprises a direct conversion receiver for correcting imbalance errors. The direct conversion receiver receives a radio frequency (RF) signal and converts the RF signal to baseband signals. The direct conversion receiver further translates the baseband signals to digital signals having a direct current (DC) offset and applies a DC offset correction to the digital signals having the DC offset to generate first DC offset corrected signals. An imbalance correction unit of the direct conversion receiver applies an imbalance correction to the first DC offset corrected signals by estimating an error between an average envelope of the first DC offset corrected signals and an average envelope of second DC offset corrected signals. The imbalance correction unit is fixed at initial imbalance parameter values. The direct conversion receiver further updates the initial imbalance parameter values of the imbalance correction unit based on the estimated error for correcting imbalance errors.
    Type: Grant
    Filed: December 8, 2011
    Date of Patent: December 17, 2013
    Assignee: Motorola Solutions, Inc.
    Inventors: Yadunandana N. Rao, Chet A. Lampert
  • Patent number: 8467755
    Abstract: A direct conversion tuner down-converts television signals, cable signals, or other signals directly from an RF frequency to an IF frequency and/or baseband, without an intermediate up-conversion step for image rejection. The direct conversion tuner includes a pre-select filter, an amplifier, an image reject mixer, and a poly-phase filter. The pre-select filter, amplifier, and the image reject mixer can be calibrated to provide sufficient image rejection to meet the NTSC requirements for TV signals. The entire direct conversion tuner can be fabricated on a single semiconductor substrate without requiring any off-chip components. The tuner configuration described herein is not limited to processing TV signals, and can be utilized to down-convert other RF signals to an IF frequency or baseband.
    Type: Grant
    Filed: December 14, 2009
    Date of Patent: June 18, 2013
    Assignee: Broadcom Corporation
    Inventor: Erlend Olson
  • Patent number: 8437430
    Abstract: Transmit IQ imbalance is calibrated and compensated for within a receiver. In at least one embodiment, a Multimedia over Coax Alliance (MoCA) Type II probe signal is transmitted from the transmitter to the receiver for use in performing transmit IQ imbalance calibration.
    Type: Grant
    Filed: December 23, 2009
    Date of Patent: May 7, 2013
    Assignee: Intel Corporation
    Inventors: Yongfang Guo, Kennan Herbert Laudel
  • Patent number: 8401509
    Abstract: A radio frequency receiver subject to a large in-band interferor employs active cancellation with coarse and at least one cancellation signals, each with a respective radio frequency combiner, in order to increase the effective dynamic range of the receiver for weak signals of interest. One or both can be digitally synthesized. This is particularly applicable for co-site interference, whereby the interfering transmit signal is directly accessible. A similar system and method may also be applied to external interferors such as those produced by deliberate or unintentional jamming signals, or by strong multipath signals. An adaptive algorithm may be used for dynamic delay and gain matching. In a preferred embodiment, a hybrid technology hybrid temperature system incorporates both superconducting and semiconducting components to achieve enhanced broadband performance.
    Type: Grant
    Filed: August 17, 2012
    Date of Patent: March 19, 2013
    Assignee: Hypres, Inc.
    Inventors: Deepnarayan Gupta, Amol Inamdar
  • Patent number: 8306166
    Abstract: A system and method for detecting burst noise during quadrature amplitude modulation (QAM) communications are provided. A QAM signal is acquired at a receiver in communication with a network. The QAM signal is demodulated at the receiver to identify a plurality of symbols. Amplitudes for each of the plurality of symbols are determined, and are compared to a predetermined threshold. For each amplitude that is greater than the predetermined threshold, information is recorded at the receiver relating to a burst noise event. The magnitude of the burst noise can be determined by measuring a difference between a received constellation point and a perimeter constellation point closest to the received constellation point. The information about the burst noise event can be transmitted to an error correction module for reducing future burst noise in the network. Equalizer coefficients and tracking loop performance can be adjusted/enhanced using the burst noise information.
    Type: Grant
    Filed: January 17, 2012
    Date of Patent: November 6, 2012
    Assignee: Casa Systems, Inc.
    Inventor: David Fox
  • Publication number: 20120258679
    Abstract: An interference signal reducing apparatus of a wireless communication system divides a signal that is input through a receiving antenna into a first signal and a second signal having a magnitude larger than that of the first signal and detects a frequency and a magnitude of an interference signal from the first signal, thereby generating an interference removal signal and then adds an interference removal signal to the signal that is input through the receiving antenna and thus reduces a magnitude of the interference signal.
    Type: Application
    Filed: April 6, 2012
    Publication date: October 11, 2012
    Applicant: Electronics and Telecommunications Research Institute
    Inventor: Dong Pil CHANG
  • Patent number: 8280314
    Abstract: A method for compensating a transceiver for impairments includes transmitting a plurality of partial bandwidth training signals using a transmitter. A plurality of response signals of a receiver having a bandwidth and exhibiting receiver impairments is captured. Each response signal is associated with one of the partial bandwidth training signals. Each of the partial bandwidth training signals is associated with a portion of the receiver bandwidth. A plurality of partial compensation filters is generated based on the plurality of response signals. Each partial compensation filter is associated with one of the response signals. The partial compensation filters are combined to configure a receiver compensation filter operable to compensate for the receiver impairments.
    Type: Grant
    Filed: June 30, 2009
    Date of Patent: October 2, 2012
    Assignee: Alcatel Lucent
    Inventors: Michael Steven Heutmaker, Walter Honcharenko
  • Patent number: 8254855
    Abstract: Techniques for identifying and suppressing frequency spurs in a signal are disclosed. In an embodiment, an incoming signal is rotated by a frequency related to a spur frequency, and an estimate of the content of the rotated signal is derived. The estimate may be subtracted from the rotated incoming signal, and the result de-rotated by the spur frequency. In an embodiment, the incoming signal may be rotated such that the spur is centered at DC. In an alternative embodiment, the estimate may be de-rotated before being subtracted from the original incoming signal. Techniques for addressing multiple spurs using serial and parallel architectures are disclosed. Further disclosed are techniques for searching for the presence of spurs in an incoming signal, and tracking spur frequencies over time.
    Type: Grant
    Filed: May 7, 2008
    Date of Patent: August 28, 2012
    Assignee: QUALCOMM, Incorporated
    Inventors: Daniel Fred Filipovic, Helena Deirdre O'Shea, Christos Komninakis, Jifeng Geng
  • Patent number: 8249540
    Abstract: A radio frequency receiver subject to a large in-band interferor employs active cancellation with coarse and fine cancellation signals, each with a respective radio frequency combiner, in order to increase the effective dynamic range of the receiver for weak signals of interest. One or both can be digitally synthesized. This is particularly applicable for co-site interference, whereby the interfering transmit signal is directly accessible. A similar system and method may also be applied to external interferors such as those produced by deliberate or unintentional jamming signals, or by strong multipath signals. An adaptive algorithm may be used for dynamic delay and gain matching. In a preferred embodiment, a hybrid technology hybrid temperature system incorporates both superconducting and semiconducting components to achieve enhanced broadband performance.
    Type: Grant
    Filed: August 5, 2009
    Date of Patent: August 21, 2012
    Assignee: Hypres, Inc.
    Inventors: Deepnarayan Gupta, Amol Inamdar
  • Patent number: 8238885
    Abstract: In order to avoid erroneous or incorrectly attributed comments in picture-assisted documentation systems, the invention proposes a system which comprises at least one mobile terminal, at least one server and at least two machine-readable markers applied to or on articles, in which the mobile terminal comprises a reading unit which can be used to read the markers applied to or on the articles, a camera for taking pictures, and means for sending pictures.
    Type: Grant
    Filed: May 29, 2007
    Date of Patent: August 7, 2012
    Assignee: NeoMedia Europe GmbH
    Inventors: Frank Mueller, Mario Joussen
  • Patent number: 8170487
    Abstract: Some embodiments provide a method, system, and apparatus for interference cancellation at the baseband of a receiver. A wireless communication device, having a transmitter and receiver, is provided with an adaptive circuit that cancels interference caused by transmit signals (or other signals) leaked or bled onto the receiver at baseband to facilitate detection of a received signal of interest. Some implementations provide for a circuit that approximately reconstructs the second and third order components caused by the nonlinear response of the down-conversion chain of a receiver. This reconstructed signal is then subtracted from the composite received signal to obtain a received signal of interest.
    Type: Grant
    Filed: February 3, 2006
    Date of Patent: May 1, 2012
    Assignee: QUALCOMM, Incorporated
    Inventors: Gurkanwal S. Sahota, Christos Komninakis
  • Patent number: 8102293
    Abstract: A digital direct conversion receiving apparatus, including: a phase conversion unit to down-convert a Radio Frequency (RF) signal into a plurality of sample signals, and generate a certain phase difference among the plurality of sample signals when the RF signal is down-converted; and a variable complex gain unit to remove an image component from the plurality of sample signals using the generated phase difference.
    Type: Grant
    Filed: September 25, 2009
    Date of Patent: January 24, 2012
    Assignee: Electronics and Telecommunications Research Institute
    Inventors: Hyung Jung Kim, Jae Hyung Kim
  • Patent number: 8019314
    Abstract: A radio communication apparatus using a direct conversion method capable of receiving a radio signal having a predetermined frequency band. The radio communication apparatus includes: a low-noise amplifier section including one or a plurality of low-noise amplifiers receiving input of a receiving signal having a predetermined frequency band; and a mixer section including in-phase and quadrature mixers demodulating an output of the low-noise amplifier into in-phase-component and quadrature-component signals, respectively, wherein the mixer section includes a capacitor in an input section, separates the in-phase component and the quadrature component by the capacitor, and supplies the components to the corresponding in-phase and quadrature mixers, respectively.
    Type: Grant
    Filed: June 11, 2008
    Date of Patent: September 13, 2011
    Assignee: Sony Corporation
    Inventor: Hitoshi Tomiyama
  • Patent number: 8000676
    Abstract: A second intercept point (IP2) calibrator and a method for calibrating IP2 are disclosed. The IP2 calibrator and the method for calibrating IP2 remove any direct current (DC) offset by comparing a common-mode reference voltage with the common-mode voltage measured between a first output terminal and a second output terminal of a mixer, and calibrates the IP2 of the mixer by comparing the common-mode voltage with a calibration reference voltage. The calibration reference voltage is independent of the common-mode reference voltage and may be a quantized variable voltage generated according to digital control code.
    Type: Grant
    Filed: November 20, 2007
    Date of Patent: August 16, 2011
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Hyun-Seok Kim, Woo-Nyun Kim
  • Publication number: 20110034141
    Abstract: A process is disclosed for minimising jammer noise in receiver systems. The process comprises the use of a primary receiver (10) and a plurality of secondary receivers (11) for receiving signals. The process comprises the steps of:—separately correlating the signal received at each of the plurality of 5 secondary receivers with the signal received at the primary receiver;—determining the magnitude of the correlation between signals received at each of the plurality of secondary receivers with the signal received at the primary receiver; and,—minimising the signal received at the primary receiver using those signals received at the secondary receivers for which the magnitude of the correlation with the signal received at the primary receiver is above a threshold value.
    Type: Application
    Filed: April 16, 2009
    Publication date: February 10, 2011
    Applicant: BAE SYSTEMS PLC
    Inventor: Peter Alan Langsford
  • Publication number: 20100317310
    Abstract: A directivity control system includes a first reception station device which receives an interference signal and a desired signal; a cooperative station device disposed at a different place from the first reception station device, which receives a signal using an antenna; and a control device which controls the directivity of an antenna of the first reception station device, wherein the control device regards a combination of the antenna of the first reception station device and the antenna of the cooperative station device as one array antenna, and calculates a sum, using a weight, of a received signal received using the antenna of the first reception station device and a received signal received using the antenna of the cooperative station device to compose a directivity pattern having a null in an arrival direction of the interference signal in the array antenna.
    Type: Application
    Filed: February 20, 2009
    Publication date: December 16, 2010
    Applicant: NIPPON TELEGRAPH AND TELEPHINE CORPORATION
    Inventors: Jun Mashino, Takatoshi Sugiyama, Kentaro Nishimori
  • Patent number: 7778613
    Abstract: A dual conversion receiver architecture that converts a radio frequency signal to produce a programmable intermediate frequency whose channel bandwidth and frequency can be changed using variable low-pass filtering to accommodate multiple standards for television and other wireless standards. The dual conversion receiver uses a two stage frequency translation and continual DC offset removal. The dual conversion receiver can be completely implemented on an integrated circuit with no external adjustments.
    Type: Grant
    Filed: April 13, 2005
    Date of Patent: August 17, 2010
    Assignee: MaxLinear, Inc.
    Inventors: Kishore Seendripu, Raymond Montemayor, Curtis Ling, Glenn Chang, Sheng Ye
  • Patent number: 7697914
    Abstract: A radio receiver front-end includes first and second RF receiver sections and an RF combining module. The first RF receiver section is coupled to receive an inbound RF signal and provide to a first representation of the inbound RF signal, wherein the inbound RF signal includes a desired signal component and an undesired signal component. The second RF receiver section is coupled to receive the inbound RF signal and to provide a second representation of the inbound RF signal. The RF combining module is coupled to combine the first and second representations of the inbound RF signal to produce a desired RF signal, wherein the desired RF signal includes the desired signal component and an attenuated representation of the undesired signal component.
    Type: Grant
    Filed: August 30, 2006
    Date of Patent: April 13, 2010
    Assignee: Broadcom Corporation
    Inventor: Ahmadreza (Reza) Rofougaran
  • Patent number: 7684777
    Abstract: In a receiving apparatus comprising a quadrature mixer (5) for mixing a radio-frequency signal with a local oscillator signal to in-phase (I) and quadrature (Q) signal components at an intermediate frequency, a polyphase filter (9) for band pass filtering the IQ signal components, and an analog-to-digital converter (13) for converting the IQ signal components into digital form, and in which receiving apparatus adjacent channel interference may occur due to IQ signal component mismatching in the quadrature mixer (5), there is provided an adjacent channel rejection device connected between the quadrature mixer (5) and the polyphase filter (9). The device comprises an analog compensation circuit (33a; 33b; 33a-b) for compensating for the IQ signal component mismatching.
    Type: Grant
    Filed: May 24, 2004
    Date of Patent: March 23, 2010
    Assignee: Infineon Technologies AG
    Inventor: Michael Lewis
  • Patent number: 7636558
    Abstract: A direct conversion tuner down-converts television signals, cable signals, or other signals directly from an RF frequency to an IF frequency and/or baseband, without an intermediate up-conversion step for image rejection. The direct conversion tuner includes a pre-select filter, an amplifier, an image reject mixer, and a poly-phase filter. The pre-select filter, amplifier, and the image reject mixer can be calibrated to provide sufficient image rejection to meet the NTSC requirements for TV signals. The entire direct conversion tuner can be fabricated on a single semiconductor substrate without requiring any off-chip components. The tuner configuration described herein is not limited to processing TV signals, and can be utilized to down-convert other RF signals to an IF frequency or baseband.
    Type: Grant
    Filed: April 25, 2006
    Date of Patent: December 22, 2009
    Assignee: Broadcom Corporation
    Inventor: Erlend Olson
  • Patent number: 7627302
    Abstract: An apparatus and method for performing digital image correction in a receiver. In one embodiment, a receiver circuit may include an IQ signal source configured to provide a digital signal comprising in-phase (I) and quadrature (Q) components, such as an IQ mixer in combination with an analog to digital converter, for example. The receiver circuit may also include an image correction unit coupled to the IQ signal source and configured to combine the digital signal with a complex image correction factor. The image correction unit may be implemented using a digital signal processor under the control of associated program instructions, for example. In one specific implementation of the receiver circuit, the image correction unit may be configured to combine the digital signal with the complex image correction factor using a cross-accumulation operation.
    Type: Grant
    Filed: June 30, 2006
    Date of Patent: December 1, 2009
    Assignee: Silicon Laboratories, Inc.
    Inventor: Tod Paulus
  • Publication number: 20090221255
    Abstract: A method of processing an in-phase signal component and a quadrature signal component of a low intermediate frequency (LIF) signal includes estimating and correcting an amplitude imbalance between a digitized in-phase signal component and a digitized quadrature signal component at a first point in time, and estimating and correcting a phase imbalance between the digitized in-phase signal component and the digitized quadrature signal component at a second point in time in response to the correcting process. The digitized in-phase signal component corresponds to the in-phase signal component at the first point in time and the digitized quadrature signal component corresponds to the quadrature signal component at the first point in time. The second point in the time is subsequent to the first point in time.
    Type: Application
    Filed: February 29, 2008
    Publication date: September 3, 2009
    Applicant: Newport Media, Inc.
    Inventors: Jun Ma, Ahmed Eltawil, Xiaoyu Fu
  • Patent number: 7558543
    Abstract: A radio frequency tuner includes a first quadrature frequency changer, I and Q filters which are electronically adjustable, and a second quadrature frequency changer. During alignment of the filters, an alignment controller connects a test tone generator to the input of the frequency converter and the generator supplies a sequence of test tones of different accurately known frequencies. The amplitude of the resulting signals at the output of one of the filters is measured by a level detector. The controller compares the measured levels with a desired frequency response and adjusts the filter accordingly. The controller then causes the generator to supply a sequence of two test tones of different frequencies and a differential phase detector measures the phase difference between the output signals of the mixers of the second frequency changer.
    Type: Grant
    Filed: May 24, 2006
    Date of Patent: July 7, 2009
    Assignee: Intel Corporation
    Inventors: Ali Isaac, Nicholas Paul Cowley
  • Patent number: 7486942
    Abstract: In a receiver, a mixer portion provided in a front-end portion thereof is built with two mixers with different input/output linearity characteristics and different current consumption. According to the electric-field strength of a received signal, or manually, one of the mixers is chosen to operate so that, when the electric-field strength is in an ordinary range, the mixer with a better input/output linearity characteristic is chosen to operate with lower current consumption and, when the electric-field strength is in a high range, the mixer that, despite operating with higher current consumption, exhibits a still better input/output linearity characteristic is chosen. The receiver thus operates with lower current consumption and lower signal distortion.
    Type: Grant
    Filed: March 31, 2005
    Date of Patent: February 3, 2009
    Assignee: Sharp Kabushiki Kaisha
    Inventor: Shoji Sakurai
  • Patent number: 7424292
    Abstract: Described are the concept, processes, and methods to combine an assortment of individually available and executable wireless mobile communication services for the purpose of achieving a desired objective(s). The activity of combining these individual services can be performed by a wireless communication user/subscriber, or a wireless communication service provider, or a wireless communication equipment supplier, or a wireless communication equipment manufacturer, etc. Once combined, these individual services represent an executable sequence that can be appropriately stored in a memory for future invocations by a user/subscriber. That is, a single invocation of the built service combination will execute the sequence of services whenever desired by a user/subscriber.
    Type: Grant
    Filed: March 11, 2004
    Date of Patent: September 9, 2008
    Inventor: Thaddeus John Kobylarz
  • Patent number: 7400873
    Abstract: The invention provides a system and method for tuning broadband signals by using post mixer I/Q equalization. An Image Rejection Mixer (IRM) is used for mixing Radio Frequency (RF) signals and rejecting image signals from the desired RF signals. The IRM includes an I/Q mixer and a filter. The I and Q paths resulting from the mixing operation in the I/Q mixer are equalized in amplitude and phase by an I/Q equalizer. Thereafter, the image signals are rejected from the desired RF signals using the filter.
    Type: Grant
    Filed: October 20, 2005
    Date of Patent: July 15, 2008
    Assignee: Anadigics, Inc.
    Inventor: John Thomas Bayruns
  • Patent number: 7373130
    Abstract: Interference suppression in a receiver in a wireless network that utilizes training sequences for synchronization and channel estimation, wherein the training sequence of an interfering channel overlaps the training sequence of a desired channel to cause degraded channel estimation, by generating a channel estimate for a carrier part of a received signal; generating a residual signal where the carrier part has been removed from the received signal; generating covariance matrix estimates for interferer channel estimate candidates; selecting carrier and interferer channel estimates having the lowest energy in the covariance matrix; and, explicitly generating the selected interferer channel estimate.
    Type: Grant
    Filed: April 13, 2005
    Date of Patent: May 13, 2008
    Assignee: Telefonaktiebolaget L M Ericsson (publ)
    Inventor: Fredrik Huss
  • Patent number: 7356317
    Abstract: A system or method for a circuit network that receives an RF signal, and where a plurality of switching transistors receive an RF signal output by the circuit network and perform mixing with a local oscillation (LO) signal received on a LO input. An active bias circuit performs active bias of the plurality of switching transistors in a feedback loop provided between the LO input and an output of the plurality of switching transistors.
    Type: Grant
    Filed: July 14, 2004
    Date of Patent: April 8, 2008
    Assignee: Silicon Storage Technology, Inc.
    Inventors: Zhiwei Xu, Pei-Ming Daniel Chow, M. Frank Chang
  • Publication number: 20080070539
    Abstract: According to a disclosed method, a calibration signal is provided at a first frequency corresponding to a low frequency edge of a desired passband to an input of a filter (240). A first value is measured at an output of the filter (240). The calibration signal is provided at a second frequency corresponding to a high frequency edge of the desired passband to the input of the filter (240). A second value is measured at the output of the filter (240). The first value is compared to the second value. A characteristic of the filter (240) is changed in response to the comparing. In one form, the filter is an IF filter (240) and a receiver (200) includes both the IF filter (240) and a calibration circuit (250) for forming the calibration signal and providing the calibration signal to the IF filter to change the characteristic in response to a calibration operation.
    Type: Application
    Filed: September 19, 2006
    Publication date: March 20, 2008
    Applicant: SILICON LABORATORIES, INC.
    Inventors: Chengming He, Richard A. Johnson, Alan F. Hendrickson
  • Patent number: 7346326
    Abstract: Disclosed is a mobile communication terminal which is provided with an equalizer function of audio equipment to adjust a timbre of transmitting/received speech sounds so as to satisfy a great number of users having various individualities and tastes simultaneously. The mobile communication terminal according to the present invention includes an equalizer connected to a CODEC, a speaker and a microphone for adjusting a timbre of an analog speech signal inputted thereto from the CODEC and/or a speech signal inputted thereto through the microphone, and an equalizer control circuit for controlling a timbre control operation of the equalizer according to a control signal of a CPU.
    Type: Grant
    Filed: December 3, 2001
    Date of Patent: March 18, 2008
    Assignee: LG Electronics Inc.
    Inventor: Hyun Kyun Kim
  • Patent number: 7228120
    Abstract: A method is provided for reducing a DC bias in a receiver. This method includes isolating a second circuit portion from a first circuit portion (535) and determining a second DC bias correction value for the second circuit portion that will eliminate a second DC bias at the isolated second circuit portion (540). The second circuit portion is then connected to the first circuit portion (550) and a bias-maximizing code word is generated at the first circuitry (505). A first DC bias correction value is then determined that will eliminate a first DC bias at the first circuit portion (555). The bias-maximizing code word is formed such that: a first integrated value of a first half of the bias-maximizing code word has a positive value, and a second integrated value of a second half of the bias-maximizing code word over half of the code word length has a negative value.
    Type: Grant
    Filed: November 18, 2004
    Date of Patent: June 5, 2007
    Assignee: Freescale Semiconductor, Inc.
    Inventors: Terence L. Johnson, Nitin Sharma, Ryan W. Lobo
  • Patent number: 7203466
    Abstract: A transmitting and receiving unit includes a receiving branch and a transmitting branch that are in each case constructed for conducting complex signals, with a control device that drives a switch by which either a phase-locked loop is switched through to frequency converters provided at the transmitting and receiving end, for providing a common carrier frequency, or in each case an independently operating PLL is provided for the transmitting and receiving branch. Such a configuration enables the transmitter, for example, to operate with direct conversion whereas the receiver can operate, for example, on the low IF principle. The invention is suitable for OFDM multi-carrier systems.
    Type: Grant
    Filed: September 26, 2003
    Date of Patent: April 10, 2007
    Assignee: Infineon Technologies AG
    Inventors: Claus Muschallik, Bernd Pflaum, Robert Sedlmaier
  • Patent number: 7203473
    Abstract: Radio equipment including a characteristic compensator for compensating for an orthogonality error of a mixer with low consumption power is disclosed. In radio equipment, an orthogonal detector converts a received real signal into a complex reception signal of an intermediate frequency. Further, when a complex reception signal converted into a digital signal by A/D converters includes a desired signal (quasi-desired signal), which includes an image signal of a non-desired signal, and a non-desired signal (preparatory desired signal), which includes an image signal of a desired signal, a frequency of the quasi-desired signal is frequency-converted to a signal closer to a direct current component by a frequency converter and a frequency of the preparatory desired signal is frequency-converted to a signal closer to a direct current component by a frequency converter. A decimator respectively performs a filtering and a down-sampling on the frequency-converted quasi-desired signal and preparatory desired signal.
    Type: Grant
    Filed: July 30, 2003
    Date of Patent: April 10, 2007
    Assignee: Samsung Electronics Co., Ltd.
    Inventor: Takahiko Kishi
  • Patent number: 7151917
    Abstract: An apparatus and method for deriving a digital image correction factor in a receiver. In one embodiment, a receiver circuit may include an error detection circuit configured to receive a digital signal comprising in-phase (I) and quadrature (Q) components and to detect an error in a complex image correction factor, and an error correction circuit coupled to the error detection circuit and configured to modify the complex image correction factor dependent upon the detected error. In one specific implementation of the receiver circuit, the error detection circuit and the error correction circuit may be coupled in a feedback loop, where the error detection circuit may be configured to iteratively detect the error in the complex image correction factor, and where the error correction circuit may be configured to iteratively correct the error.
    Type: Grant
    Filed: September 29, 2003
    Date of Patent: December 19, 2006
    Assignee: Silicon Laboratories, Inc.
    Inventor: Tod Paulus
  • Patent number: 7142835
    Abstract: An apparatus and method for performing digital image correction in a receiver. In one embodiment, a receiver circuit may include an IQ signal source configured to provide a digital signal comprising in-phase (I) and quadrature (Q) components, such as an IQ mixer in combination with an analog to digital converter, for example. The receiver circuit may also include an image correction unit coupled to the IQ signal source and configured to combine the digital signal with a complex image correction factor. The image correction unit may be implemented using a digital signal processor under the control of associated program instructions, for example. In one specific implementation of the receiver circuit, the image correction unit may be configured to combine the digital signal with the complex image correction factor using a cross-accumulation operation.
    Type: Grant
    Filed: September 29, 2003
    Date of Patent: November 28, 2006
    Assignee: Silicon Laboratories, Inc.
    Inventor: Tod Paulus
  • Patent number: 6947718
    Abstract: A compensating part compensates for deviations on transmission paths, and a pre-deviation signal combining part or a post-deviation signal combining part combines signals on the transmission paths before or after having the deviations applied thereto, wherein the compensating part performs compensation for the deviations based on output of the pre-deviation signal combining part or post-deviation signal combining part and the signals on the transmission paths to be compensated.
    Type: Grant
    Filed: February 6, 2002
    Date of Patent: September 20, 2005
    Assignee: Fujitsu Limited
    Inventor: Shuji Kobayakawa
  • Patent number: 6915112
    Abstract: An active cancellation controller receives a signal strength indicator that indicates a power level of a coupled signal from a local wireless transmitter at a local wireless receiver. The active cancellation controller tunes an active cancellation circuit to reduce the signal strength indicator. The active cancellation circuit is to generate a cancellation signal to combine with the coupled signal at the local wireless receiver.
    Type: Grant
    Filed: November 12, 2000
    Date of Patent: July 5, 2005
    Assignee: Intel Corporation
    Inventors: Todd Sutton, Carlos Soledade
  • Patent number: 6826392
    Abstract: A multipath noise reducer extracts a high-frequency signal from a demodulated signal obtained from a frequency-modulated signal, and generates a noise reduction coefficient from the extracted high-frequency signal. The demodulated signal is also separated into high-frequency and low-frequency components, the high-frequency component is multiplied by the noise reduction coefficient, and the resulting product is added to the low-frequency component. An output signal is thereby obtained in which the spike noise that characterizes multipath reception of a frequency-modulated signal is reduced with relatively little distortion of other parts of the signal, including the parts between noise spikes. The distortion can be further reduced by replacing the demodulated signal with an interpolated signal during noise spikes before the low-frequency component is separated.
    Type: Grant
    Filed: March 12, 2002
    Date of Patent: November 30, 2004
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Masayuki Tsuji, Masahiro Tsujishita, Kenichi Taura, Masayuki Ishida