Nortel Networks Corporation

Russell Smiley

Bradley John Morris

Steve Andre Beaudin

Arthur Thomas Gerald Fuller

Johan M Grundlingh

John Ilowski

Robert Leroux

Paul Astell

Arthur Fuller

In cellular telephony, a plurality of communication signals which are received at a base station for wireless transmission are multiplexed onto a single physical medium which runs up a mast. This reduces the use of cabling running up the mast with an attendant savings in cost.

Cellular telephony mast cable reduction

Methods and apparatus are provided for efficiently coupling singly terminated networks with doubly terminated networks. An isolation network is disposed between a singly terminated network and a doubly terminated network. The isolation network is a three terminal device having an input terminal connected to the output of the singly terminated network and having an output terminal connected to the input of the doubly terminated network. An isolation terminal is provided that receives and dissipates energy reflected from the input of the doubly terminated network, such that substantially no energy is received or seen by the output of the singly terminated network.

Method and apparatus for dual use of singly and doubly terminated networks

Methods and apparatus are provided for efficiently combining and filtering a plurality of input signals into a single combined output signal. M number of input signals are received, combined and filtered by a filter/combiner. The filter/combiner has a plurality of input stages for each input signal, and an output stage that combines the outputs of the input stages into the combined signal. The filter/combiner has a desired overall filter transfer function designed to filter signals having frequencies outside a passband and which passes the desired M input signals.

Method and apparatus for combining multiple signals for high efficiency applications

Methods and apparatus are provided for efficiently amplifying or converting a signal. An input signal is decomposed into a plurality of two state signals, each two state signal having a respective on level and off level. This may involve sigma-delta modulation and phase splitting. For amplifier applications, each of the two state signals is amplified with a respective switching power amplifier to produce a respective amplified signal. The amplified signals are combined to produce an amplified version of the input signal. Signals may be adjusted for impairments associated with a subsequent processing operation such as the combining.

High-efficiency amplifier, converter and methods

Methods and apparatus are provided for efficiently amplifying a signal. An input signal is decomposed into a plurality of two state signals, each two state signal having a respective on level and off level. This may involve sigma-delta modulation and phase splitting. Each of the two state signals is amplified with a respective switching power amplifier to produce a respective amplified signal. The amplified signals are combined to produce an amplified version of the input signal.

High-efficiency amplifier and method

A biasing method and apparatus which provides bias circuits of radio frequency (RF) power transistors with a low reactive impedance at low frequencies to reduce hysteresis related distortion without affecting the transistor input or output impedance or any impedance matching network which may be used. In one embodiment, reduced hysteresis within a lateral diffused metal-oxide semiconductor (LDMOS) transistor is brought about by a drain bias circuit without any impact on the transistor output impedance. By removing the effect of the bias circuit at RF frequencies, the bias circuit can be designed with a low reactive impedance at low frequencies without any material consequences on the transistor output impedance. With a low enough reactive impedance, the hysteresis introduced by the bias circuit is substantially reduced. An auxiliary bias feed external to an RF transistor package is also embodied.

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Nepean, Canada

Russell Smiley