Abstract: In some examples, a circuit includes an amplifier, a resistor, and a damping network. The amplifier has an amplifier output and first and second amplifier inputs. The first amplifier input is adapted to be coupled to a first terminal, and the second amplifier input is configured to receive a reference voltage. The resistor is coupled between the amplifier output and the first amplifier input. The damping network is coupled between the amplifier output and the first terminal.

Abstract: An audio signal processing device comprises: an audio input configured to receive an audio signal to be coded; an audio codec configured to apply audio coding to the audio signal, thereby generating coded audio data, having an audio bandwidth, for transmission to a remote device; a network interface configured to receive from the remote device an indication of at least one characteristic of an audio output device of the remote device; and an audio bandwidth selector configured to set an audio bandwidth parameter of the audio codec based on the indication received from the remote device, thereby setting the audio bandwidth of the coded audio data in dependence on the at least one characteristic of the audio output device.

Abstract: A gain control system for dynamically tuning an echo canceller, the echo canceller being configured to estimate an echo of a far-end signal and subtract that estimate from a microphone signal to output an echo cancelled signal, the system comprising an echo measurement unit configured to calculate a ratio of the microphone signal to the far-end signal, an attenuation unit configured to attenuate at least one of the microphone signal and the far-end signal to output a second microphone signal and a second far-end signal to the echo canceller, the ratio of the second microphone signal to the second far-end signal being different from the calculated ratio, and an attenuation controller configured to control the attenuation unit, in dependence on the calculated ratio, so as to alter the ratio of the second microphone signal to the second far-end signal and control the echo-cancelled signal.

Abstract: A gain control system for dynamically tuning an echo canceller, the echo canceller being configured to estimate an echo of a far-end signal and subtract that estimate from a microphone signal to output an echo cancelled signal, the system comprising an echo measurement unit configured to calculate a ratio of the microphone signal to the far-end signal, an attenuation unit configured to attenuate at least one of the microphone signal and the far-end signal to output a second microphone signal and a second far-end signal to the echo canceller, the ratio of the second microphone signal to the second far-end signal being different from the calculated ratio, and an attenuation controller configured to control the attenuation unit, in dependence on the calculated ratio, so as to alter the ratio of the second microphone signal to the second far-end signal and control the echo-cancelled signal.

Abstract: A method and apparatus to gate an ultrasonic emitter operation includes a housing including the ultrasonic emitter, where the ultrasonic emitter is operable to periodically transmit an ultrasonic pulse of a predefined frequency. A microphone circuit is disposed in the housing, such that the microphone circuit is operable to receive a reflected ultrasonic signal derived from the transmitted ultrasonic pulse. A controller is coupled to the emitter and the microphone circuit, where the controller operable to gate the operation of the emitter to an OFF state based on at least one measured parameter of the reflected ultrasonic signal. The parameters can include a Doppler measurement and a distance measurement.

Abstract: A computer-implemented method of providing matching information to prospective first and second users is performed at a server, the method including: receiving first audio data and first user information; receiving second audio data, and second user information; storing a first timestamp of the first audio data and first user information and a second timestamp of the second audio data and second user information; performing analysis processing on the first audio data to obtain first feature information, and performing analysis processing on the second audio data to obtain second feature information; judging whether the first timestamp and the second timestamp and the first feature information and the second feature information match; and if the first and second times of receipt and the first and second feature information match, sending the first user information to the second user and sending, by the server, the second user information to the first user.

Abstract: A hybrid device can be configured to execute operations to select singleton coordinating functionality in a hybrid communication network. In one embodiment, a single master device (e.g., a hybrid device configured as both a registrar and a central access point (CAP)) can be selected. The hybrid device can transmit search messages to detect an existing master device and/or to identify other hybrid devices contending to become the master device. The hybrid device with the preferred device identifier is selected as the master device. In another embodiment, operations for selecting the coordinating functionality are split into two independent stages—a CAP selection stage and a registrar selection stage. In the CAP selection stage, the hybrid device with a preferred device weight (or a preferred device weight and a preferred device identifier) is configured as the CAP. In the registrar selection stage, similar operations can be executed to select the registrar.

Abstract: A parallel hybrid circuit comprising a transformer, a first matching resistor, a second matching resistor and an echo cancelling circuit. The transformer comprises: a first side, comprising a transmitting coil group and a receiving coil group, wherein the transmitting coil group comprises at least one transmitting coil, wherein the receiving coil group comprises at least one receiving coil; a second side comprising at least one transceiving coil; wherein the transformer receives a transmitting signal and couples the transmitting signal from the first side to the second side via a first turn ratio, and receives a receiving signal from the transceiving line and couples the receiving signal from the second side to the first side via a second turn ratio. The first, second matching resistors are coupled with the transformer in parallel. The echo cancelling circuit is coupled between the transmitting line and the receiving line.

Abstract: An integrated hybrid circuit includes a transmission unit, a transceiver coil, a transceiver circuit, a hybrid matching circuit, and a receiving circuit. The transmission unit generates a pair of upstream signals according to a user transmission signal. The transceiver coil transmits the pair of upstream signals to a central office through a pair of twisted pair, and receiving a pair of downstream signals from the central office through the pair of twisted pair. The hybrid matching circuit receives an adjustment signal to adjust selective impedances. The receiving circuit receives the pair of downstream signals from the central office, and generates the adjustment signal according to downstream and upstream rates and signals from the hybrid matching circuit. The transmission unit adjusts transmission power and bandwidth of the transmission unit and the receiving unit adjusts filter bandwidth of the receiving unit according to the adjustment signal for optimizing upstream and downstream rates.

Abstract: 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.

Abstract: A method of generating a plurality of supply voltages for a plurality of subscriber line channels includes generating a first target VBAT value for a first associated linefeed driver from a first VBAT control. A second target VBAT value for a second associated linefeed driver is generated from a second VBAT control. A selected target VBAT value is generated based upon the first and second target VBAT values. A magnitude of the selected target VBAT value is not less than any maximum of a magnitude of the first and second target VBAT values. A switching regulator is controlled to provide a first generated VBAT corresponding to the selected target VBAT value, wherein the switching regulator provides a second generated VBAT having a pre-determined proportional relationship (p) to the first generated VBAT.

Abstract: An internet protocol telephone includes a substrate having an input and an output that are capable of being connected to the internet protocol (IP) network. A relay is disposed on the substrate and is connected between the input and the output of the substrate. The relay includes first and second native FETs that have a threshold voltage of approximately zero volts. Therefore, the relay is nominally turned-on, even when little or no voltage (or power) is applied to the IP telephone substrate, as during the discovery mode of IP telephone operation. During discovery mode, The IP phone is configured to be responsive to extended link pulses and block data packets that are associated with legacy devices. Data packets have a higher signal duration and are more continuous than extended link pulses. The IP phone includes a switchable ground that is connected to the gates of the native devices, and is controlled by a rectifier and filter circuit that are connected to the substrate input.

Abstract: A differential transformer-free hybrid circuit includes a first amplifier configured to receive a first signal from a transmitter and output the first signal to a telephone loop, and a second amplifier configured to receive a second signal from the telephone loop and output the second signal to a receiver. Further, the differential transformer-free hybrid circuit also includes at least one balanced network element and a transformer-less interface configured to couple the first amplifier and the second amplifier to the telephone loop, wherein the transformer-less interface includes at least one current blocking device.

Abstract: An enhanced sidetone system is disclosed which provides the user of a telecommunications terminal, while speaking, with immediate audio feedback that corresponds to what the far-end party is probably hearing. The sidetone system continuously samples the input speech signal from the user and also obtains signal quality statistics of the transmission path. These statistics can include descriptions of network quality-of-service characteristics (e.g., packet loss rate, etc.) and/or media quality characteristics (e.g., audio distortion due to echo cancellation, etc.). These statistics enable the disclosed technique to determine whether the transmitted signal quality is acceptable. When an unacceptable condition in transmit-path signal quality is detected, the technique modifies the traditional (main) sidetone signal.

Abstract: A power transformation device of a powered device in a power over Ethernet system includes a first transformer coupled between a first pin and a second pin of an Ethernet terminal, a second transformer coupled between a third pin and a sixth pin of the Ethernet terminal, and a bridge rectifier coupled between a center tap of the first transformer and a center tap of the second transformer, for rectifying power outputted from the center taps of the first transformer and the second transformer, so as to provide power for the powered device.

Abstract: A method of calibrating longitudinal balance for a subscriber line interface circuit includes providing a first and a second driver of a differential driver pair for driving a subscriber line. An output of each of the first and second drivers is coupled to a common output. The common output is coupled to an input of the first driver. The gain of at least one of the first and second drivers is adjusted until a calibration signal (V1) present at the input of the first driver is substantially the same as a calibration signal (V2) present at the input of the second driver.

Abstract: A system for improving the attenuation of an undesired signal found in a differential signal path through the use of inductive coupling. The system includes a primary inductor, a secondary inductor, and a filter. The primary inductor and the secondary inductor operably couple an input differential signal pair to an output differential signal pair, and the filter attenuates an undesired signal in the output differential signal pair.

Abstract: An xDSL modem having an adaptive hybrid termination impedance. The modem has a transformer with two cores, one connected to the modem's receiver and the other connected to the modem's transmitter. The two cores share an adjustable termination impedance. The modem determines which impedance setting to use, based on one or more measurements of channel loss, local echo power and received power from the far end transmitter, and the like.

Abstract: A telephone interface circuit comprises a first transistor for controlling opening and closing between a speech circuit and subscriber lines, a second transistor for controlling the first transistor to turn on and off, a positive feedback circuit connecting a collector terminal of the first transistor and a base terminal of the second transistor, an overcurrent detection circuit detecting overcurrent applied to the subscriber lines, and a breaker circuit for turning off the first transistor by lowering the base potential of the second transistor to a low potential when overcurrent is detected at the overcurrent detection circuit. Here, the base terminal of the first transistor and a collector terminal of the second transistor are connected. Further, when off-hook, the base potential of the second transistor is controlled in such a manner as to become a high potential by a microcomputer.

Abstract: Methods and apparatus for communicating include coupling first and second devices with a first unidirectional data line, a second unidirectional data line, and a clock line. Frames of data are serially communicated between the first and second devices using the first and second unidirectional data lines. The frame format of a frame carried by the first unidirectional data line is distinct from a frame format of a frame carried by the second unidirectional data line. Each frame is synchronized with a clock signal carried by the clock line.

Abstract: A document scanning device reads an image on a document while scanning the image, and generates image data based on the image. The document scanning device selects and sets a scanning speed in accordance with a transfer mode used when the document scanning device transfers the image data to another apparatus. The document scanning device controls the amount of generated image data by using the set scanning speed to successively read the image, whereby optimal transfer processing in accordance with the transfer mode can be performed. By switching a transfer path in accordance with the type of the read data, i.e., binary data per pixel or multilevel data per pixel, efficient data transfer can be performed.

Abstract: A method and apparatus for isolating transmit and receive signals in a communication system utilizing a common channel for both incoming and outgoing signals. In one embodiment a tuned hybrid or isolation circuit is provided with a high-frequency pre-emphasis response. The tuned hybrid rejects the transmit signal from the receive port and is capable of isolating the low power receive signal. One or more filters within the hybrid provide the desired levels of attenuation and frequency specific processing. Outgoing transmit signals encounter minimal attenuation thereby reducing overall transmit power requirements while receive signals are isolated. The tuned hybrid may be configured with an all-pass network consisting of an attenuator and a delay element. Both of these devices or elements maybe tuned to tailor the frequency response to the channel.

Abstract: A differential transformer-free hybrid circuit includes a first amplifier configured to receive a first signal from a transmitter and output the first signal to a telephone loop, and a second amplifier configured to receive a second signal from the telephone loop and output the second signal to a receiver. Further, the differential transformer-free hybrid circuit also includes at least one balanced network element and a transformer-less interface configured to couple the first amplifier and the second amplifier to the telephone loop, wherein the transformer-less interface includes at least one current blocking device.

Abstract: A telephone line interface and side-tone attenuation circuit includes two opto-electric converters. The first has an input interconnected to receive a signal proportional to a near-end signal, and an output interconnected to modulate a current proportional to the near-end signal onto the subscriber loop. The second has its input interconnected to provide a signal proportional to a current on the subscriber loop, including the current proportional to the near-end signal, at its output. A summing amplifier receives signals proportional to the output voltage of the second opto-electric converter and a signal proportional to the near-end signal. The output voltage of the second opto-electric amplifier includes a component that is substantially 180° out of phase with the near-end signal, allowing the near-end signal to be cancelled at the summing amplifier.

Abstract: The invention concerns a method and a device for automatically adapting the levels of signals exchanged in a telephone network, between a first set and a second set. The method is characterized in that it consists in the following steps: digitizing the signal coming from the transmission line and received by the first set; on the basis of the digital data translating the signals exchanged with the transmission line; estimating the transfer function equal to the ratio of the signal received by the first set over the signal transmitted by the first set; respectively multiplying each of the exchanged signals by an appropriate gain determined on the basis of the estimated value of said transfer function. The invention is particularly applicable to telephones, videophones, fax machines or computers connected to a communication network.

Abstract: A transceiver for a transmission and reception signal which can be transmitted via a signal line having a particular line impedance (ZLINE), having a line driver (6) for driving a transmission signal via the signal line and having an analog echo cancellation filter (15) for signal suppression for an echo signal brought about by the transmission signal, where the line driver (6) has a synthesized output impedance (RSYN), with the line driver (6) having a downstream hybrid circuit (11) for connecting an analog echo cancellation filter (15).

Abstract: A method and apparatus for isolating transmit and receive signals in a communication system utilizing a common channel for both incoming and outgoing signals. In one embodiment a tuned hybrid or isolation circuit is provided with a high-frequency pre-emphasis response. The tuned hybrid rejects the transmit signal from the receive port and is capable of isolating the low power receive signal. One or more filters within the hybrid provide the desired levels of attenuation and frequency specific processing. Outgoing transmit signals encounter minimal attenuation thereby reducing overall transmit power requirements while receive signals are isolated. The tuned hybrid may be configured with an all-pass network consisting of an attenuator and a delay element. Both of these devices or elements maybe tuned to tailor the frequency response to the channel.

Abstract: An ADSL POTS splitter includes low pass filter. The low pass filter includes a first inductor portion in communication with the line interface and a second inductor portion isolated from the line interface via an isolation capacitor. In one embodiment, the first inductor portion is characterized for non-saturation in conventional operating ranges. The first non-isolated inductor portion has a respective DC saturation current and the isolated inductor portion has a respective DC saturation current. The DC saturation current of the first non-isolated inductor portion is substantially greater than the DC saturation current of the isolated inductor portion for achieving higher inductance in the isolated inductor portion.

Abstract: The present invention relates to a transceiver for bidirectional frequency division multiplexed transmission, a communication system including one or more transceivers. Optionally, the communication system is a communication system for a digital subscriber line. The transceiver comprises transmission means with a voltage source output or a current source output for transmitting data in a transmission frequency range, receiving means for receiving data in a receiving frequency range, and a coupling impedance for connecting the transmission means and the receiving means to a transmission medium. The magnitude of the coupling impedance in the transmission frequency range is smaller than the magnitude of the coupling impedance in the receiving frequency range if the transmission means has a voltage source output and is higher than the magnitude of the coupling impedance in the receiving frequency range if the transmission means has a current source output.

Abstract: A hybrid with a plurality of selectable hybrid input paths each having an associated hybrid input path filter is provided. The hybrid includes a plurality of selectable receive paths each having an associated receive path filter. The hybrid further includes a hybrid output. The selection of any filter is non-mutually exclusive to the concurrent selection of another filter.

Abstract: An improved data access arrangement device for use in full-duplex two-wire communication systems having a transmission impedance characteristic. The DAA includes a transmit amplifier and a receive amplifier adapted for connection to a two-wire line, a codec connected to the transmit amplifier for generating a transmit signal, a summation device connected to the receive amplifier, an echo cancellation path including a variable gain amplifier, where the path extends between the codec and the summation device, and wherein the variable gain amplifier is adjusted in accordance with the transmission impedance characteristic. The variable gain amplifier may include a gain register that is programmed by a microprocessor, or may have the gain set by user-configurable switches. The summation device is preferably an operational amplifier.

Abstract: A line interface includes a transmit path for an electrical signal, a receive path for an electrical signal, and a reference path coupled from the output of the transmit path to the receive path. The reference path including a filter for matching the impedance of the telephone line. The transmit path has an output coupled to the primary winding of a transformer. The secondary winding of the transformer is adapted to be coupled to a telephone line. The receive path has an input coupled to the primary winding and the reference path includes means for inverting an electrical signal, thereby providing a hybrid coupling function.

Abstract: A hybrid matching system is disclosed for use with a transmitter and receiver. The hybrid matching system includes a pair of transmitter output nodes for providing a differential transmitter signal for transmission, a pair of receiver input nodes for receiving a differential received signal, a pair of line terminals to interface with a transmission line. The system also includes a first transformer having a first set of windings and a second set of windings, and a second transformer having a first set of windings and a second set of windings. The first set of windings of the first transformer is coupled to the transmitter output nodes. The second set of windings of the first transformer is coupled to the first set of windings of the second transformer. The second set of windings of the second transformer is coupled to the pair of line terminals.

Abstract: A gigabit ethernet line driver includes a transmitter having both transmitter and active hybrid outputs. The transmitter consists of a plurality of transmitter clusters each connected to both the transmitter and active hybrid outputs. Each transmitter cluster includes a plurality of transmitter cells consisting of a driver cell and digital to analog converter connected to driver cell. A hybrid circuit connects between the transmitter outputs and receiver inputs for separating a receiver signal from the transmitter signal responsive to a tuning signal.

Abstract: A faster modem apparatus communicates with customer premise equipment according to a variety of communication protocols. The faster modem apparatus communicates with customer premise equipment comprising an analog soft-modem comprising a codec. A method utilizes an unused portion of the codec operating range to code and decode data signals having frequencies above 4 kHz. The faster modem apparatus also codes and decodes data signals above 4 kHz. The analog soft-modem and the faster modem apparatus transmit and receive coded analog signals at a signal level of greater than ?9 dBm. In one embodiment, the faster modem apparatus is also operative to communicate with additional modems such as dial-up modems and DSL modems. In one embodiment, the faster modem apparatus supports simultaneous voice and data communications.

Abstract: A method is provided for accomplishing asymmetric digital subscriber loop classification and the design of passive hybrid networks for each of the classes. The resulting hybrids are suitable for implementation in a switchable hybrid architecture.

Abstract: A line interface performs echo cancellation without the use of a hybrid filter network and includes a transmit path having a line driver, a single matching network terminating the line, and a single transformer. The transformer uses split windings on both the primary side and the secondary (line) side. Each half of the primary side is tapped to obtain a turns ratio of N1:N2, while each half of the secondary side of the transformer has N windings. The single matching impedance is coupled in parallel between the first winding and the second winding on each half of the primary side. Either the voltage across the matching impedance or the voltage across the receive terminals is bootstrapped to the receive signal through multiple negative feedbacks. The transfer function of the line driver is shaped as a first-order high-pass filter (HPF) to reject any out-of-band noise and distortion components.

Abstract: A monolithic transceiver integrated circuit that includes a substrate, a transmitter subsystem of one or more subcircuits on the substrate, and a receiver subsystem of one or more subcircuits on the substrate. Also included is a bias current supply coupled to the receiver and transmitter subsystems to provide bias current. The bias current supply includes a first bias circuit on the substrate coupled to, and to supply bias current to, a first subcircuit of the transmitter subsystem. The first bias circuit includes a first current modulator having a first switch input to indicate that the bias current is to start or stop being supplied to the first subcircuit. The first current modulator is to control the rate of change of supplied bias current in response to the first switch input. The first subcircuit may be a power amplifier. The control of the rate of change reduces oscillator pull in at least one oscillator included in the integrated circuit.

Abstract: A level of a sound signal including a voice signal and an environmental noise signal is detected and a level (power level) is sampled in response to a clock signal. It is detected whether the presently sampled level increases from the previously sampled level. An environmental noise level is estimated such that, when the presently sampled level increases from the previously sampled level, difference between the presently and previously estimated environmental noise levels is lower than a predetermined value. When the presently sampled level decreases, the presently estimated environmental noise level is equalized to the presently sampled value. The environmental noise level is estimated only when the detected level is smaller than the predetermined value. The sampling interval may be smaller than 250 msec. Estimation may be stopped in the presence of voice signal. An environmental noise level may be estimated when the detected level is smaller than a reference.

Abstract: A hybrid circuit that couples a broadband modem to a POTS or ISDN telecommunication line (TL) and includes a transformer bridge circuit (TBC) that includes a bridge circuit (BC). The bridge circuit includes four legs formed by impedance matching networks and parts of the transformer, and a differential drive amplifier (DRV) that performs impedance synthesis. A secondary winding (TS) of the transformer is magnetically coupled to the first and the second primary windings and is electrically coupled to the telecommunication line. First and second impedance dividers (Zhin1, Zhout1 and Zhin2, Zhout2) are connected to the various nodes to provide outputs to a receive amplifier (RCV). The impedance matching networks (Zm1; Zm2) include various passive and reactive components that together provide an impedance value selected based upon the line impedance reflected into the primary windings (TP1; TP2) of the transformer.

Abstract: A directional coupler for a modem has a high common mode noise rejection characteristic with low transmit signal leakage, and reduced distortion of components mixed with a received signal. A primary filter network is connected to a communications circuit. The primary filter network has an output connected to an input of an amplifier. A feedback network is connected between the input and output of the amplifier. The primary filter network, the amplifier and the feedback network are arranged to provide a virtual ground at the input of the amplifier, and a filter characteristic which attenuates frequencies in the transmit signal band. The advantage is reduced component count while providing excellent transmit signal rejection and reducing received signal distortion.

Abstract: A method and apparatus is provided for performing an active impedance differential current feedback. A signal is received. A current feedback of an output signal in an active feedback synthesis mode is performed based upon the signal. The active current feedback includes using an active feedback network for conditioning an output signal, converting the signal into a differential current signal, and summing at least two components of the differential current signal for performing a differential feedback.

Abstract: An XDSL system comprising a hybrid circuit in operative communication with a transmission line and an XDSL modem associated with a subscriber premises. The hybrid circuit comprises a plurality of selectable impedance circuits having different impedance values. A controller selectively engages each of the impedance circuits in-line with the XDSL modem and the transmission line. The controller records the performance of the modem with each circuit engaged, and selects the desired impedance circuit as a function of the performance characteristics associated with each of the impedance circuits. The impedance circuit which provides the best performance characteristic is selected as the impedance circuit for normal modem operation.

Abstract: A method for accessing a device, such as a memory device and an interface device, by a processor is disclosed. The method involves the processor requesting access permission for the transfer of data. The bridge device grants access permission. The processor in response to the granting of access permission indicates that the processor is busy with the access. The processor also generates address and control signals for the access. The bridge device indicates that data is ready for transfer. A processing system including the processor and the bridge device is also disclosed.

Abstract: A network communication device and hybrid circuit thereof. The hybrid circuit includes a first transformer, a second transformer and a protector electrically connected between the primary winding of the first transformer and the primary winding of the second transformer for protecting transmission function of internet and inhibiting interference of low-frequency signals generated during the communication process.

Abstract: An integrated line inductor and line feed resistor is disclosed. A first coil winding and a second coil winding having a select resistance are magnetically coupled to each other. The first coil winding and second coil winding are each operable to transform electric energy between a Subscriber Line Interface Circuit (SLIC) and a tip and ring (T/R) line.

Abstract: A method of and apparatus for optimizing signal transformation from a twisted pair transmission line to a combination transmitter and receiver for a frame-based communications network, the transmitter having a transmit output pair port for transmitting signals onto the frame-based communications network over the twisted pair transmission line, the receiver having a receive input pair port for receiving signals from the frame-based communications network over the twisted pair transmission line. A transformer is coupled between the twisted pair transmission line and each of the transmit output pair port and the receive input pair port. The transformer has a coil across the twisted pair, a transmit coil across the transmit output pair port, and a receive coil across the receive input pair port. A transfer ratio between the transmit coil and the coil across the twisted pair is optimized for transmitting signals.

Abstract: A hybrid circuit is disclosed for effectively communicating information over a telecommunications line to which a transmitter and receiver are connected. The hybrid circuit is configured as a filter for filtering at the receiver input signals at predetermined frequencies appearing on the transmitter output and the telecommunications line. The filter circuit additionally forms a capacitive divider for scaling signals appearing at the transmitter output and canceling the scaled signals at the receiver input with related signals appearing on the telecommunications line. In one embodiment of the present invention for communicating using the ADSL protocol, the filter circuit is a first order high pass filter.

Abstract: Apparatus for supplying power to communication devices operating within a Local Area Network (LAN) over LAN cabling, the communication devices including one or more powered devices adapted to receive power over the LAN cabling, the apparatus including a power supply which is adapted to receive power from an unregulated source and to provide therefrom regulated power. The apparatus further includes power distribution and control circuitry, which is adapted to identify the powered devices on the LAN, to receive the regulated power and to generate therefrom respective output voltages for supply to the powered devices. The apparatus is housed in a chassis which retains the power supply and the power distribution and control circuitry as a single module.

Abstract: A hybrid system with adjustable on-chip components and a method calibrating the same invariably maximizes hybrid performance despite of on- and off-chip component mismatches and imperfections. The hybrid system has a main DAC, a replica DAC, and three or four resistors. Both DACs are directly connected to digital data. An adjustable resistor is connected to the main DAC and is calibrated such that output impedance is automatically adjusted to match an off-chip load impedance Z. A replica DAC current K is calibrated for optimum DC matching in presence of Z. An adjustable capacitor C2 is calibrated for slope-matching (bandwidth matching). If Z changes, the calibration procedure should be repeated for optimal performance. These three calibration mechanisms can be utilized individually or in combination. The present invention is compatible with both analog and digital echo-cancellers.