Ikanos Communications, Inc.

Globespan, Inc.

Globespan Virata Corporation

Globespan Semiconductor, Inc.

Brooktree Broadband Holding, Inc.

Fujitsu Corporation

Arnold Muralt

Frode Larsen

Laurent Alloin

Daniel Amrany

Laurent Pierrugues

Christian Eichrodt

William Edward Keasler, Jr

Drahoslav Lim

George S Moschytz

Vinay Kumar Chapala

James T Schley May

Danny Amrany

William H Scholtz

Nianxiong Tan

Vipin Pathak

Robin Levonas

Peter D Keller

Jung-Lung Lin

Francis R Ashley

Eduard Sackinger

Laszlo Arato

Markus Helfenstein

Gabe P Torok

Sam Olu George

Fenghua Zheng

Fred Larsen

Frank Ashley

Min Shen

Armando Geday

The present invention relates to methods and apparatuses for sensing noise sources in a wireline communications environment such as a customer premises environment in a DSL system. In embodiments, the invention includes an additional sensor that is connected to power mains in a DSL customer premises environment either to characterize, at their source, noises coupling into the DSL lines, and/or to mitigate their impact into the DSL lines. One objective is associated with diagnostics that help to better characterize the noise signals themselves and derive correlation of signals sensed from the power mains and their possible projection onto the DSL line. Another objective makes use of these power line sensor signals to mitigate or to eliminate power line noises that make their way onto the DSL line. Example embodiments further include and exploit signals from additional secondary sensors such as secondary common mode, differential mode and phantom mode sensors.

Method and apparatus for sensing noise signals in a wireline communications environment

The present invention relates generally to addressing performance issues in xDSL communication systems, and more particularly to methods and apparatuses to measure and characterize CM noise impacting a DSL line in a customer premises, measurements and characterization of the projection of these CM signals in Differential Mode (DM), and finally a derivation of an estimate of the loop balance.

Methods and apparatuses for characterizing common mode noise and estimating loop imbalance

The present invention relates to a method by which an xDSL modem can be properly connected and/or optimally tuned to achieve a desired performance goal based on knowledge obtained by first performing a SELT test and then post-processing the results of that test. In embodiments, the processed SELT results are used to detect bad connections or other anomalies such as split pairs. In embodiments, the processed SELT results are used to configure programmable components and filters in the analog front end in a manner that achieves the performance goal. In these and other embodiments, the performance goal is to maximize the attainable data rate. As such, through various hardware design options and configurations according to the invention, the performance of the modem can be tuned such that even in the presence of undesirable loop characteristics, adequate, or even good performance, can be achieved.

Method and apparatus of optimizing an xDSL transceiver configuration using single ended line test (SELT) measurement

One embodiment is a method for performing 2-wire line imbalance measurements. The method comprises receiving a probe signal and based on the probe signal, determining one of more of: an estimated transverse conversion loss (TCL) coupling transfer function and an estimated transverse conversion transfer loss (TCTL) coupling transfer function.

Systems and methods for performing line imbalance measurement and mitigation based on a common mode sensor

An adaptive hybrid system is coupled to a loop for adjusting trans-hybrid loss. The system comprises a fixed portion comprising a first receiver transfer function block and a first hybrid transfer function block. The fixed portion is configured to receive a far-end signal and mitigate frequency dependent attenuation experienced by the far-end signal. The system also comprises a variable portion comprising a second receiver transfer function block and a second hybrid transfer function block configured to subtract a transmit echo from the received far-end signal.

Adaptive integrated hybrid with complex adaptation for digital subscriber line systems

A system and a method for constructing a signal integrity supervisor capable of both detecting and triggering an appropriate response when transmit path signals indicate a potential damaging transmitter operating mode. The system and method of the present invention takes advantage of the inherent property of a Delta-Sigma Modulator (DSM) which makes the probability of encountering a long string of consecutive ones or zeroes during nominal operation very small. The signal integrity supervisor ensures safe transmitter operation by monitoring the data and the clock inputs to a digital to analog converter. The system may comprise a data signal supervisor and a clock signal supervisor. The data supervisor may comprise a comparator and a counter and may be configured to power down a line driver upon detecting a data stream having a continuous voltage level. The clock detector may comprise a pair of monostable circuits, an inverter, and a NAND gate and may be configured to reset the transmitter if a 'missing' clock signal state is detected. The present invention can also be viewed as providing a method for preventing a transmission unit from forwarding signals that may result in a DC flow condition. In its broadest terms, the method can be described as: monitoring a data signal; generating a first output signal in response to a data signal having an anomalous condition; monitoring a clock signal; and generating a second output signal in response to clock signal having an anomalous condition.

System and method for implementing a delta-sigma modulator integrity supervisor

A single unified digital subscriber line (DSL) transceiver can be used for DSL applications, can be integrated on a single board or chip, or within a less board space. An embodiment of the unified DSL transceiver comprises a transmit circuit coupled to a line driver/transformer circuit. The line driver/transformer circuit is coupled to a receive circuit that comprises a switching circuit. A signal is transmitted from the transmit circuit to the line driver/transformer circuit; the switching circuit is configured based on DSL applications, and the signal is propagated from the line driver/transformer circuit to a line.

Unified DSL transceiver

An improved analog front end and methods for increasing the power efficiency of duplex signals on a transmission line are disclosed. The improved analog front end bifurcates a hybrid into a fixed portion and an adaptive portion. The adaptive portion combines a biquad and a summer to produce a filter transfer function suited to compensate for transmission line irregularities. A method for configuring a local transceiver to minimize power requirements at a remote transmitter is disclosed. Broadly the method entails, applying a transmit signal to a front end in the absence of a remote signal; optimizing the transmit signal power; recording the reflected transmit signal; applying an adaptive filter in response to transmission line irregularities; and controllably adjusting the adaptive filter to minimize the amplitude of the reflected version of the transmit signal in the receive path. A method for recovering a remotely generated signal is also disclosed. The method entails, applying a local transmit signal to the front end in the absence of a remote signal; recording a reflected version of the transmit signal in the receive path; controllably adjusting an adaptive portion of the front end to minimize the amplitude of the reflected version of the local transmit signal; and combining a scaled replica of the local transmit signal with a plurality of adaptive filter outputs to recover a remotely generated receive signal from the transmission line.

Circuit and method for an improved front end in duplex signal communication systems

An improved line driver and method for increasing the power efficiency, signal accuracy, and stability of a transmit signal on a transmission line are disclosed. The improved line driver uses a negative feedback control loop, thereby enhancing operational stability and suppressing both amplifier imperfections and discrete component manufacturing variances. Furthermore, when the improved line driver output stage is integrated with a hybrid, the composite circuit provides a power efficient full duplex solution for line driver applications. In a preferred embodiment, the improved line driver may comprise an active line termination control loop with current sense feedback, a first amplifier, and a second amplifier. The present invention can also be viewed as providing a method for increasing the stability, power efficiency, and accuracy of a line driver in a duplex transmission system. In its broadest terms, the method can be described as: applying a transmit signal to an input stage of a line driver; amplifying the transmit signal; using an active termination feedback control loop to generate a feedback signal; amplifying the feedback signal; combining the feedback signal with a duplex signal on a transmission line to generate a scaled transmit signal; and combining the scaled transmit signal with the duplex signal to recover a remotely generated receive signal from the transmission line.

Circuit and method for active termination of a transmission line

A system and a method for constructing a signal integrity supervisor capable of both detecting and triggering an appropriate response when transmit path signals indicate a potential damaging transmitter operating mode. The system and method of the present invention takes advantage of the inherent property of a Delta-Sigma Modulator (DSM) which makes the probability of encountering a long string of consecutive ones or zeroes during nominal operation very small. The signal integrity supervisor ensures safe transmitter operation by monitoring the data and the clock inputs to a digital to analog converter. The system may comprise a data signal supervisor and a clock signal supervisor. The data supervisor may comprise a comparator and a counter and may be configured to power down a line driver upon detecting a data stream having a continuous voltage level. The clock detector may comprise a pair of monostable circuits, an inverter, and a NAND gate and may be configured to reset the transmitter if a &ldquo;missing&rdquo; clock signal state is detected. The present invention can also be viewed as providing a method for preventing a transmission unit from forwarding signals that may result in a DC flow condition. In its broadest terms, the method can be described as: monitoring a data signal; generating a first output signal in response to a data signal having an anomalous condition; monitoring a clock signal; and generating a second output signal in response to clock signal having an anomalous condition.

An improved line driver and method for increasing the available signal transmit power on a transmission line are disclosed. The improved line driver achieves an available transmit power increase without increasing the maximum current in the line driver output stage. The output stage of the line driver may comprise a first amplifier, a second amplifier, and an integrated back-matching resistor network. In order to further increase the available transmit power; a protective semiconductor device may be added to a line driver output stage for each semiconductor device in the first and second amplifiers. A third embodiment of a line driver output stage in accordance with the present invention may comprise a combination of the integrated back-matching resistor network along with the protective semiconductor devices. In its broadest terms, the method for increasing the available signal transmit power on a transmission line of the present invention can be described as: applying a transit signal to an input stage of an integrated line driver; amplifying the transmit signal such that the output signal swing exceeds the maximum drain-source voltage of the integrated circuit technology used to implement the line driver amplifier(s); and applying the amplified transmit signal via an integrated back-matching resistor network to the transmission line.

Increased output swing line drivers for operation at supply voltages that exceed the breakdown voltage of the integrated circuit technology

Growing community of inventors

Fair Haven, NJ, United States of America

Arnold Muralt