National Semiconductor Corporation

Other

Intel Corporation

Iti Scotland Limited

Duncan James Bremner

James B Wieser

Eivind Johansen

Mark Norris

Ray Allen Reed

Finn Helmer

Roger K Benton

Dean Kemp

Helmer Finn

Johansen Eivind

Antenna

An optical network may be configured dynamically so that a given channel wavelength can operate in either direction over a fiber in a network. Thus, network providers can provision bandwidth according to the traffic characteristics of the network link in question. A plurality of transceiver modules on either side of a fiber may be switched from a transmit mode to a receive mode depending on the desired direction of the channel.

Asymetric optical network traffic flow control

A signal line driving circuit with power control for selectively reducing internal power dissipation when driving an external load. While driving the external load with a constant current the output voltage generated across such load is monitored. If the load impedance decreases sufficiently to cause the output voltage to fall below a predetermined threshold value and, therefore, cause the voltage across the signal line driving circuit to increase, the magnitude of the power supply voltage is automatically reduced, thereby reducing the voltage across the signal line driving circuit. Such a signal line driving circuit is particularly advantageous as a subscriber line interface circuit (SLIC). As the subscriber goes from an on-hook condition to an off-hook condition and if the subscriber loop is sufficiently short (or low in impedance), a lower power supply voltage is used to minimize the power dissipation of the SLIC while still maintaining the required subscriber loop current.

Signal line driving circuit with self-controlled power dissipation

A transient signal detector for monitoring a signal line and generating a control signal which indicates when the magnitude of a differential signal on the line exceeds either a positive or negative threshold value. The threshold value is defined by a single current, thereby allowing for a single, simple adjustment of such threshold in both the positive and negative directions.

Transient signal detector

A subscriber line interface circuit which includes a transient signal detector with temporal hysteresis. During steady state operation, the drive current for the subscriber loop allows the loop to respond to changes in loop conditions according to a steady state time constant of the loop filter. Upon detection of a line voltage transient which exceeds a predetermined threshold in either a positive or negative direction, the filter time constant is significantly reduced (e.g., 100:1) and held at such reduced value following the initial transient and for a predetermined time period after the line voltage has fallen back below such predetermined threshold. This allows the transient conditions to be fully compensated prior to resetting the filter time constant back from the lower transient value to the higher steady state value.

Transient signal detector with temporal hysteresis

A capacitive multiplier circuit for an integrated circuit includes a capacitor coupled between a first node and a second node. A current source is coupled to provide a controlling current to the second node. A first current path shunts the first node and a second current path shunts the second node. The first current path is a first transistor having its conductance path connected between the first node and the substrate and its control electrode connected to the first node. The second current path is a second transistor having its conductance path connected between the second node and the substrate and its control electrode connected to the first node. The current ratio between the two current paths will be determined by the relative areas of the respective conductance paths.

Capacitive multiplier for timing generation

A signal interface circuit with selectable signal interface parameters for a telephone subscriber line includes an impedance circuit having a selectable impedance value, signal terminals having an associated, definable termination impedance, a transmitter circuit having a definable transmitter transfer function and a receiver circuit having a definable receiver transfer function. The signal terminals connect to an external signal line pair having an associated line impedance for conducting outgoing and incoming signals therefrom and thereto, respectively. The transmitter circuit receives the outgoing signal from the signal terminals and provides a transmit signal in accordance with its transmitter transfer function. The receiver circuit, which includes a differential transconductance amplifier, receives an input signal and the transmit signal and provides the incoming signal to the signal terminals in accordance with its receiver transfer function. The termination impedance, transmitter transfer function and receiver transfer function are all defined by the selectable impedance, with the termination impedance defined to match the line impedance.

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Lochwinnoch, United Kingdom

Duncan James Bremner