Patents Assigned to Broadcom
  • Publication number: 20020006173
    Abstract: A method and a system for providing an input signal from a multiple decision feedback equalizer to a decoder based on a tail value and a subset of coefficient values received from a decision-feedback equalizer. A set of pre-computed values based on the subset of coefficient values is generated. Each of the pre-computed values is combined with the tail value to generate a tentative sample. One of the tentative samples is selected as the input signal to the decoder. In one aspect of the system, tentative samples are saturated and then stored in a set of registers before being outputted to a multiplexer which selects one of the tentative samples as the input signal to the decoder.
    Type: Application
    Filed: February 27, 2001
    Publication date: January 17, 2002
    Applicant: Broadcom Corporation
    Inventors: Oscar E. Agazzi, David Kruse, Arthur Abnous, Mehdi Hatamian
  • Publication number: 20020000880
    Abstract: An extended range variable gain amplifier is described. The variable gain capability is achieved by replacing differential pair amplifiers having an input signal with less attenuation with one having an input signal that is more attenuated. This replacement continues until only ten differential pair amplifiers are remaining. At this point, if less gain is desired, differential pair amplifiers are turned off, but are not replaced. A minimum number of amplifiers will remain on.
    Type: Application
    Filed: July 3, 2001
    Publication date: January 3, 2002
    Applicant: Broadcom Corporation
    Inventors: Lawrence M. Burns, Leonard Dauphinee
  • Publication number: 20020001384
    Abstract: Provided is an architecture (hardware implementation) for an authentication engine to increase the speed at which multi-loop and/or multi-round authentication algorithms may be performed on data packets transmitted over a computer network. Authentication engines in accordance with the present invention apply a variety of techniques that may include, in various applications, collapsing two multi-round authentication algorithm (e.g., SHA1 or MD5 or variants) processing rounds into one; reducing operational overhead by scheduling the additions required by a multi-round authentication algorithm in such a matter as to reduce the overall critical timing path (“hiding the ads”); and, for a multi-loop (e.g., HMAC) variant of a multi-round authentication algorithm, pipelining the inner and outer loops.
    Type: Application
    Filed: April 4, 2001
    Publication date: January 3, 2002
    Applicant: Broadcom Corporation
    Inventors: Mark Buer, Patrick Y. Law, Zheng Qi
  • Publication number: 20020000882
    Abstract: A protection circuit for extending the dynamic range of an amplifier circuit is described. Off-chip impedances, such as inductors, cause the output of the circuit to swing above and below the bias voltage. A protection circuit is included, either on-chip or off-chip, to protect the integrated circuit components if there is a fault condition in either of the off-chip impedances.
    Type: Application
    Filed: July 26, 2001
    Publication date: January 3, 2002
    Applicant: Broadcom Corporation
    Inventors: Lawrence M. Burns, Leonard Dauphinee
  • Patent number: 6335933
    Abstract: In a frame-switched network, a sender sends frames to a receiver over a possibly unreliable channel. Sent frames include frame identifiers that can be used for a limited automatic repeat request. Upon receipt of a frame, the receiver determines, from the frame identifier, if frames prior to the received frame were lost in transit. If the receiver determines that it missed a prior frame, the receiver sends the sender a negative acknowledgment (nack) for the missed prior frame or frames. Otherwise, if the receiver receives a frame correctly, it does not acknowledge the frame. The frame identifiers can be a set of sequential integers with frames transmitted in sequential frame order. In some embodiments, when a receiver receives a frame out of order, the receiver buffers the out of order frame in a receiver buffer for a receive buffer period until preceding frames are received or a receive buffer period expires.
    Type: Grant
    Filed: May 21, 1999
    Date of Patent: January 1, 2002
    Assignee: Broadcom HomeNetworking, Inc.
    Inventor: Tracy D Mallory
  • Patent number: 6335935
    Abstract: A network switch for network communications includes a first data port interface supporting a plurality of data ports transmitting and receiving data at a first data rate. A second data port interface supports a plurality of data ports transmitting and receiving data at a second data rate. A CPU interface is configured to communicate with a CPU, and an internal memory communicates with the first data port interface and the second data port interface. A memory management unit is provided, including an external memory interface, for communicating data from at least one of the first data port interface and the second data port interface and an external memory. A communication channel is provided, for communicating data and messaging information between the first data port interface, the second data port interface, the internal memory, and the memory management unit.
    Type: Grant
    Filed: June 30, 1999
    Date of Patent: January 1, 2002
    Assignee: Broadcom Corporation
    Inventors: Shiri Kadambi, Shekhar Ambe
  • Patent number: 6335932
    Abstract: A data switch for network communications includes at least one first data port interface which supports a plurality of data ports which transmit and receive data at a first data rate. At least one second data port interface is provided; the at least one second data port interface supports a plurality of data ports transmitting and receiving data at a second data rate. A CPU interface is provided, with the CPU interface configured to communicate with a CPU. An internal memory is provided, and communicates with the at least one first data port interface and the at least one second data port interface. A memory management unit is provided, and includes an external memory interface for communicating data from at least one of the first data port interface and the second data port interface and an external memory.
    Type: Grant
    Filed: June 30, 1999
    Date of Patent: January 1, 2002
    Assignee: Broadcom Corporation
    Inventors: Shiri Kadambi, Shekhar Ambe
  • Publication number: 20010056417
    Abstract: A method and apparatus for searching an electronically stored table of information including a plurality of table entries and facilitating high speed searching of a table to provide a longest matching entry. The table searching method uses at least one memory unit having a table of information including a plurality of data entries. The table of information has a plurality of search keys associated with the plurality of data entries and the plurality of search keys form a tree structure based on a prefix length for each of the search keys. The plurality of search keys are expanded such that each of the plurality of search keys has two lowest level search keys associated therewith that cover a lowest level of the tree structure. A binary search of the lowest level search keys is performed based on a search value to determine a longest prefix match. A data entry of the plurality of data entries is output based on said longest prefix match.
    Type: Application
    Filed: May 22, 2001
    Publication date: December 27, 2001
    Applicant: Broadcom Corporation
    Inventors: Jun Cao, Brandon Carl Smith, Eric Ng
  • Publication number: 20010055335
    Abstract: A method is provided for reducing power dissipation within a communications system having a plurality of adaptive filters with a plurality of taps, each tap is switchable between an active and an inactive state, each tap also has a coefficient. An acceptable error for the system is specified. This error is typically the mean squared error of the system. A tap threshold is set for each active tap. Those taps having a coefficient with an absolute value less than the tap threshold set for the active tap are deactivated. The error of the system is computed and compared to the acceptable system error. If the computed system error is less than the acceptable system error, the tap threshold for each active tap is increased.
    Type: Application
    Filed: August 15, 2001
    Publication date: December 27, 2001
    Applicant: Broadcom Corporation
    Inventors: Oscar E. Agazzi, John L. Creigh, Mehdi Hatamian
  • Publication number: 20010055319
    Abstract: A number of features for enhancing the performance of a cable transmission system in which data is transmitted between a cable modem termination system at a headend and a plurality of cable modems located different distances from the headend. The power transmission level, slot timing, and equalization of the cable modems are set by a ranging process. Data is transmitted by the modems in fragmented form. Various measures are taken to make transmission from the cable modems robust. The upstream data transmission is controlled to permit multiple access from the cable modems.
    Type: Application
    Filed: February 9, 2001
    Publication date: December 27, 2001
    Applicant: Broadcom Corporation
    Inventors: Thomas J. Quigley, Jonathan S. Min, Lisa V. Denney, Henry Samueli, Sean F. Nazareth, Feng Chen, Fang Lu, Christopher R. Jones
  • Publication number: 20010055331
    Abstract: Various systems and methods providing high speed decoding, enhanced power reduction and clock domain partitioning for a multi-pair gigabit Ethernet transceiver are disclosed. ISI compensation is partitioned into two stages; a first stage compensates ISI components induced by characteristics of a transmitter's partial response pulse shaping filter in a demodulator, a second stage compensates ISI components induced by characteristics of a multi-pair transmission channel in a Viterbi decoder. High speed decoding is accomplished by reducing the DFE depth by providing an input signal from a multiple decision feedback equalizer to the Viterbi based on a tail value and a subset of coefficient values received from a unit depth decision-feedback equalizer. Power reduction is accomplished by adaptively truncating active taps in the NEXT, FEXT and echo cancellation filters, or by disabling decoder circuitry portions, as channel response characteristics allow.
    Type: Application
    Filed: February 9, 2001
    Publication date: December 27, 2001
    Applicant: Broadcom Corporation
    Inventors: Oscar E. Agazzi, John L. Creigh, Mehdi Hatamian, David E. Kruse, Arthur Abnous, Henry Samueli
  • Patent number: 6332004
    Abstract: A power efficient and reduced electromagnetic interference (EMI) emissions transmitter for unshielded twisted pair (UTP) data communication applications. Transmit data is converted to a current-mode analog waveform by a digital-to-analog converter (DAC). A discrete-time analog filter is integrated with the DAC line driver to provide additional EMI emissions suppression. A multiplicity of output cells produce an output signal that is responsive to a plurality of digitized input data samples. A timing circuit generates timing signals for dividing each digitized input data sample into a first time segment and a second time segment. A control logic connected to each output cell generates control signals to drive each output cell to produce a portion of the output signal for the first time segment and the full output signal for the second time segment.
    Type: Grant
    Filed: October 29, 1999
    Date of Patent: December 18, 2001
    Assignee: Broadcom Corporation
    Inventor: Kevin T. Chan
  • Patent number: 6327311
    Abstract: The present invention provides a frequency-diverse single-carrier modulation scheme that extends the usable SNR range of severely distorted channels. This scheme is advantageous for applications in which when the SNR is low and the transmitted spectrum contains unusable regions (e.g., spectral nulls due to radio-frequency interference ingress or egress). In one embodiment, the symbol baud rate is selected in order that unusable portions of the frequency response of the transmission channel are mapped onto usable portions of the frequency response of the transmission channel.
    Type: Grant
    Filed: October 9, 1998
    Date of Patent: December 4, 2001
    Assignee: Broadcom Homenetworking, Inc.
    Inventor: Eric J. Ojard
  • Patent number: 6326852
    Abstract: A high precision charge pump used in a phase-lock-loop incorporating a phase/frequency detector is designed and constructed to substantially eliminate the effects of DC offset and glitch errors on the charge pump output current. The high precision charge pump is constructed of parallel current paths each having a central node which is, in turn, connected to a feedback element. The feedback element defines a feedback current which is applied to the charge pump so as to maintain the two central nodes at an equi-potential level and to maintain the value of the pump-down current exactly equal to the value of the pump-up current output by the device.
    Type: Grant
    Filed: August 28, 2000
    Date of Patent: December 4, 2001
    Assignee: Broadcom Corporation
    Inventor: Myles H. Wakayama
  • Patent number: 6317858
    Abstract: A method for decoding an algebraic-coded message including determining a discrepancy indicator; determining an error locator polynomial according to a modified Berlekamp-Massey algorithm such that an uncorrectable message is detected; and producing a perceptible indication of the detected uncorrectable message. An apparatus includes storage devices, arithmetic components, and an uncorrectable message detector.
    Type: Grant
    Filed: November 9, 1999
    Date of Patent: November 13, 2001
    Assignee: Broadcom Corporation
    Inventor: Kelly Cameron
  • Patent number: 6316933
    Abstract: An on-chip test bus circuit for testing a plurality of circuits and an associated method. The test bus circuit consists of a test bus and a plurality of switching circuits which selectably provide electrical connections between the respective circuits and the test bus. The plurality of switching circuits are configured to transfer an electrical charge between a node disposed within each switching circuit not selected to provide an electrical connection and a respective charge source or sink. The charge source or sink may consist of a low-impedance, substantially noise-free DC voltage or signal source.
    Type: Grant
    Filed: August 26, 1999
    Date of Patent: November 13, 2001
    Assignee: Broadcom Corporation
    Inventor: Erlend Olson
  • Patent number: 6310909
    Abstract: A method for enhancing the bit rate and/or margin at which quadrature amplitude modulation (QAM) communication is performed includes the steps of varying a spectral allocation and constellation size with which communication is performed, so as to define a combination of spectral allocation and constellation size at which the bit rate and/or margin are enhanced. The spectral allocation can be varied by varying a stop frequency thereof, while maintaining a substantially constant start frequency, so as to mitigate undesirable high frequency content of the bandwidth. Alternatively, both start and stop frequencies may be varied.
    Type: Grant
    Filed: May 11, 1999
    Date of Patent: October 30, 2001
    Assignee: Broadcom Corporation
    Inventor: David Jones
  • Publication number: 20010034216
    Abstract: The present invention provides a method for determining nonlinear distortion of a transmitter. A test symbol sequence is transmitted from the transmitter under test as an analog output signal. The analog output signal is sampled to produce a first sequence which represents the test symbol sequence as distorted by a linear distortion sequence and a nonlinear distortion sequence. The test symbol sequence is filtered via an adaptive filter to produce a second sequence such that the second sequence is approximately equal to the test symbol sequence as distorted by the linear distortion sequence. The second sequence is subtracted from the first sequence to produce an output sequence substantially equal to the nonlinear distortion sequence.
    Type: Application
    Filed: February 22, 2001
    Publication date: October 25, 2001
    Applicant: Broadcom Corporation
    Inventors: John L. Creigh, Oscar E. Agazzi
  • Patent number: 6307905
    Abstract: A method for reducing system performance degradation caused by switching noise in a system which includes a set of subsystems. Each of the subsystems includes an analog section and a digital section. Each of the analog sections operates in accordance with a corresponding one of a set of sampling clock signals which are synchronous in frequency. The digital sections operate in accordance with a receive clock signal. The receive clock signal is generated such that it is synchronous in frequency with the sampling clock signals and has a phase offset with respect to one of the sampling clock signals. This phase offset is adjusted such that system performance degradation due to coupling of switching noise from the digital sections to the analog sections is substantially minimized.
    Type: Grant
    Filed: November 9, 1999
    Date of Patent: October 23, 2001
    Assignee: Broadcom Corporation
    Inventor: Oscar E. Agazzi
  • Publication number: 20010032201
    Abstract: A table searching system for facilitating high speed linear searching of a table of information by a plurality of searching agents is provided. The system includes: a memory unit for storing a table of information including a plurality of data entries each having data contents; a plurality of searching agents each being communicatively coupled with the memory unit, and having a port for receiving an associated search key value; and a memory controller unit providing a centralized interface between the memory unit and each of the agents, the controller unit being operative to control the memory unit to provide the contents of a current one of the table entries to each of the agents during each of a plurality of cycles of operation. Each of the searching agents is operative to determine an associated best matching one of the data entries based on comparisons between the associated key value and the contents of the data entries provided by the memory unit.
    Type: Application
    Filed: March 8, 2001
    Publication date: October 18, 2001
    Applicant: Broadcom Corporation
    Inventors: Dennis Sungik Lee, Michael Veng-Chong Lau, Pei-Feng Adrian Wang, Chuen-Shen Bernard Shung