Nortel Networks Corporation

Flex Ltd.

Dan V Gorcea

Robert McLaren Thomas

Gyula G Jakab

Carl C Anderson

Kevin R Parker

Jose Noel N Manceau

David W Foster

A set of headphones include a zone that is sensitive to electromagnetic radiation, a first earpiece including a first directional antenna operable at a first frequency and having a first radiation pattern radiating away from the zone, and a second earpiece including a second directional antenna operable at the first frequency and having a second radiation pattern radiating away from the zone.

Devices, systems, and methods for directional antennas that protect sensitive zones

An antenna structure includes a first conductive element including a first planar portion, and an extension portion that extends away from the first planar portion at a center of the first planar portion. The antenna structure may include a second conductive element spaced apart from the first planar portion and electrically connected to the extension portion.

Antennas and devices, systems, and methods including the same

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.

Directional receiver coupling arrangement with frequency selectivity and gain control for DSL

A DSL modem comprises an additional transformer and additional coils on a coupling transformer to couple a received signal on a transmission line to a receive path without loss due to an active impedance. The ratio of windings on the coils allows gain to be introduced to improve the signal to noise ratio.

Method and design for increasing signal to noise ratio in xDSL modems

The current technology involved with overlaying any type of digital subscriber loop (xDSL) service with plain old telephone service (POTS) makes use of two separate transformers, one for POTS and another for xDSL. This invention provides a transformer which combines the POTS transformer and the xDSL transformer into one transformer. This considerably reduces the weight volume and cost of the overlaid POTS and xDSL circuits. In combining the two transformers the magnetic coupling between any one of the windings used for POTS and any one of those used for xDSL must remain weak despite their close proximity. In addition, any two windings of the same type of service, either POTS or xDSL, must remain strongly coupled. This is achieved by choosing a special geometric form for the core and choosing strategic locations for the windings. A portion of the core is dedicated to serve as a shunt for each component of the magnetic field produced by the windings. Strongly coupled windings are wound around a same portion of the core whereas weakly coupled windings are wound around different core portions which are separated by the shunt.

Transformer arrangement for combined pots and xDSL service

Line receiver with improved dynamic range

A line driver for connection to a transmission line having a characteristic impedance. The line driver can be arranged in a voltage-mode or a current-mode configuration. In the voltage-mode configuration, the line driver comprises an amplifier, a transformer, a reference resistor and a feedback circuit. The first winding of the transformer has a first end connected to the output of the amplifier and the second winding is connectable to the transmission line. The reference resistor has an end connected to the second end of the first winding at a junction point and the feedback circuit is connected to the input and output of the amplifier and also to the junction point. The reference resistor has a resistance equal to {fraction (1/k)} times the characteristic impedance of the transmission line. The feedback circuit is arranged to produce a voltage at the output of the amplifier substantially equal to &minus;(K&minus;1) times the voltage at the junction point, for a predetermined value of K. This results in a synthesized output impedance equal to the characteristic impedance of the transmission line, while losses in the reference resistor are reduced. At the same time, the gain is easily set by the specifying the resistance of a source resistor placed at the input to the amplifier.

High-efficiency line driver

Combined active impedance and filter in line drivers

Generation of a compensation signal for canceling the distortion component of a distorted signal at an affected node, where the distortion component is caused by electro-magnetic coupling from a distortion-causing signal source. The distortion-causing signal is coupled into a distortion cancellation system using capacitive or electro-magnetic coupling techniques, resulting in the generation of an induced voltage. The induced voltage is fed to an impedance network and then to a plurality of cells, one for each of the affected nodes. The compensation signal appearing at the output of the cell is combined with the distorted signal at the corresponding affected node. By appropriately selecting the impedance values of the components in the corresponding cell, substantial cancellation of the distortion from the distortion-causing signal source can be achieved. The system can be simplified if the degree to which the distortion-causing signal source couples into the distorted signal is determined ahead of time.

System for cancelling distortion in an electronic circuit

A power amplifier receives an input analog signal and generates a corresponding power amplified output analog signal. The power amplifier includes first and second power supply rails, an amplifier circuit, and a switch circuit. The first and second power supply rails are capable of supplying power having respective first and second predetermined levels, and a single predetermined polarity. The amplifier circuit is connected to receive the input analog signal and adapted to generate the output analog signal. Finally, the switch circuit is adapted to selectively connect one of the first and second power supply rails to the amplifier circuit.

High efficiency dual supply power amplifier

The invention is an amplifier configuration which provides signal gain at very low levels of distortion. The inventive amplifier configuration consists of two amplifiers whose outputs are added to give the total amplified signal. A first amplifier functions in the usual way, amplifying a signal from a voltage source and having a controllable feedback gain. A second amplifier is also fed by the voltage source but applies a feedback gain to the total amplified signal rather than to its own output signal. By selecting the feedback gains to be substantially identical, portions of voltage waveforms that have been removed or altered due to clipping or other forms of distortion are restored by the second amplifier. The invention is particularly useful when amplifier gain is low, e.g., at high frequencies. Suitable implementations are in the voltage domain, using operational amplifiers, or in the current domain, using, for example, voltage-controlled current sources.

Low-distortion high-frequency amplifier

The invention is an improvement to an amplifier configuration employing an amplification stage (e.g., an operational amplifier) biased via biasing terminals and a follower stage (e.g., an emitter-follower BJT pair), the follower stage being capable of producing the same voltage as the amplification stage but at a higher current. The improvement consists of feeding a fraction of the output voltage of the follower stage to the biasing terminals of the amplification stage. Specifically, the output of the follower stage is connected to the biasing terminals via a common bootstrap resistor and respective capacitors. The capacitors behave as a DC block and as an AC short-circuit. The biasing terminals are then connected to respective biasing resistors which could then be connected to respective supply voltage sources. In this way, the maximum permitted amplitude of the output voltage is increased, leading to less distortion and less frequent saturation of transistors in the amplification stage.

Growing community of inventors

Kanata, Canada

Dan V Gorcea