摘要:
A XDSL line card including an allocator for allocating power to the multi-tone modulated communications on each of the subscriber lines, and for selecting control parameters sufficient to effect communications on each of the subscriber lines at a power level proximate to an allocated power level therefore. The line card also includes configurable components coupled to one another to form a transmit path and a receive path to couple to the digital subscriber lines. The configurable components are responsive to the control parameters selected by the allocator to initialize multi-tone communications over each of the plurality of subscriber lines at a power level proximate the allocated power level.
摘要:
A XDSL line card including an allocator for allocating power to the multi-tone modulated communications on each of the subscriber lines, and for selecting control parameters sufficient to effect communications on each of the subscriber lines at a power level proximate to an allocated power level therefore. The line card also includes configurable components coupled to one another to form a transmit path and a receive path to couple to the digital subscriber lines. The configurable components are responsive to the control parameters selected by the allocator to initialize multi-tone communications over each of the plurality of subscriber lines at a power level proximate the allocated power level.
摘要:
A transceiver having shared and discrete components forming a transmit path and a receive path configured to couple to a communication medium for establishing a multi-tone modulated communication channel thereon. The transceiver includes a line driver component on the transmit path. The line driver is configured to respond to a protocol determination and by configuring at least one of a transmit power level and a transmit bandwidth of the multi-tone modulated communication channel on the communication medium. The line driver includes a plurality of pre-amplifiers each exhibiting a combination of transmit power and bandwidth for amplification of a transmit signal modulated with a selected multi-tone modulation protocol. The line driver also includes a single output amplifier having an output coupled to the communication medium and an input switchably coupled to an output of a selected one of the plurality of pre-amplifiers in response to the protocol determination.
摘要:
A current controller includes impedance elements coupled to form at least one impedance ladder circuit which exhibits a fixed impedance at an input and current divider steps each differing in a current magnitude by a multiple of three with respect to the current magnitude in an adjacent less significant step. Single pole triple throw (SPTT) switchably couple an associated step in the impedance ladder circuit to one of three outputs. Three discrete current sources or sinks are each coupled to a corresponding one of the outputs of each of the SPTT switches. The digital driver is coupled to each control input of each SPTT switch to additively deliver selected ones of the stepped currents from each step of the impedance ladder circuit to a corresponding selected one of the current sources or sinks.
摘要:
A line driver for coupling a data transceiver to a transmission line having a load impedance via a transformer with a turns ratio of 1:n includes an input port for receiving an input signal voltage from the data transceiver, an output port for supplying an output signal voltage to the transformer, and an amplifier circuit for amplifying the input signal voltage. The amplifier circuit includes a first output stage, a second output stage coupled to the output port, an output resistor coupled to the first output stage, a feedback path from the first output stage to an input of the amplifier circuit, and a line matching network coupled between the first output stage and the second output stage, for compensating variations in the load impedance, so that a synthesized output impedance of the line driver substantially matches an actual load impedance Z of the transmission line.
摘要:
A read channel circuit of an optical disk reproducing apparatus is adapted to provide stability in servo control and reduce power consumption by revising the offset component of the circuit components after application of reference signals and then the offset component caused by pit depth resulting from signals read out in reproducing a data from an optical disk. The read channel circuit includes: a data converting section for amplifying signals input via different channels and converting them to digital data. A data reproducing section is provided for summing and waveform-equalizing the digital signals, detecting the phase difference between the waveform-equalized signals and reference sampling points, and generating a sampling clock frequency which is provided to the data converting section for compensating for the phase difference. A servo error signal detecting signal is provided for delaying the signals input from the data converting section by phases specified by the offset revision control signal and the pit depth revision control signal, summing the delayed signals into a plurality of signals, and generating the tracking error signals based on the comparison of phase differences between the summed signals.
摘要:
A balance gain tuning apparatus including a first amplifying part amplifying one of signals output from a optical pickup to a fixed gain; a second amplifying part amplifying another signal of the signals output from the optical pickup to a tunable gain; a subtracting part producing a difference of an output of the first amplifying part and that of the second amplifying part; and a servo control part tuning the gain of the second amplifying part in response to an output of the subtracting part.
摘要:
A preamplifier for an optical disc system. The preamplifier is based on an automatic gain control (AGC) system for obtaining a constant response and a stable output signal for input signals of a certain amplitude. The preamplifier includes a radio frequency amplifier for amplifying an output signal from the pick-up unit, an AGC unit for amplifying an output signal from the radio frequency amplifier to a desired level, an AGC detector unit coupled at its input terminal to an output terminal of the AGC unit and at its output terminal to an input terminal of the AGC unit. The AGC detector unit serves to rectify an output signal from the AGC unit, compare the rectified signal with a reference signal having a predetermined level, and send the resultant signal obtained by the comparison to the AGC unit. A mode selecting unit is coupled to the AGC detector unit and adapted to select one of several modes of operation, respectively corresponding to different equalization characteristics.
摘要:
An amplifier including complementary push and pull components, a bias component and a quiescent current balancer. The complementary push and pull components are serially coupled to one another between an electrical source and sink to generate an output signal at a common output terminal responsive to the input signal source. The bias component is coupled between the input signal source and the complementary push-pull components to bias the input signal to the push component and the input signal to the pull component by discrete amounts which reduce cross-over clipping exhibited in the output signal. The quiescent current balancer is coupled to the output terminal to balance quiescent currents in the push and the pull component at discrete levels which equilibrate amplification levels of the input signal generated by the push component and the pull component in the output signal at the output terminal.
摘要:
A method and circuit control a quiescent current of an amplifier including a preamplifier, error amplifiers, and output devices driven by the error amplifiers, the error amplifiers having an input-referred offset voltage. The method includes (a) applying a calibration voltage to an input of the error amplifiers, (b) calibrating a quiescent current of the output devices by changing the calibration voltage so that the calibrated quiescent current has a predetermined current value, the calibration voltage corresponding to the calibrated quiescent current being set as a correction voltage, and (c) operating the amplifier with the correction voltage applied to the input of the error amplifiers. The circuit includes a correction voltage generator supplying a correction voltage to the error amplifier input, a quiescent current detector detecting the quiescent current, and a calibration circuit adjusting the correction voltage so that the quiescent current is calibrated to a predetermined current value.