Amplix

Mitec Telecom Inc.

Said Touimer

Ammar B Kouki

Fadhel M Ghannouchi

Fran&ccedil;ois Beauregard

Chan-Wang Park

Fadhel Ghannouchi

Ahmed A Boutouili

An active predistorting linearizer with agile bypass circuit for safe mode operation is used in conjunction with an amplifier. This linearizer comprises a controllable input variable-attenuator and drive-amplifier circuit supplied with the input signal to attenuate and amplify the input signal. A predistorter includes a controllable phase-shifting and amplitude-adjusting path supplied with the attenuated and amplified input signal to distort the latter signal and produce a predistorted output signal. A controllable output variable-attenuator and drive-amplifier circuit is supplied with the predistorted output signal to attenuate and amplify this predistorted output signal before supplying it to the power amplifier. A phase-shifting and amplitude-adjusting controller is connected to the controllable input variable-attenuator and drive-amplifier circuit, the controllable phase-shifting and amplitude-adjusting path, and the controllable output variable-attenuator and drive-amplifier circuit. Finally, a bypass extends in parallel with the series circuit including the serially interconnected input variable-attenuator and drive-amplifier circuit, controllable phase-shifting and amplitude-adjusting path, and output variable-attenuator and drive-amplifier circuit. This bypass defines a bypass circuit established in response to a fault condition in the series circuit to bypass the faulty series circuit.

Active predistorting linearizer with agile bypass circuit for safe mode operation

A linearizer channel amplifier for use in conjunction with a power amplifier comprises an input series circuit formed of a first variable attenuator, an input drive amplifier and a power limiter, and an output series circuit formed of a second variable attenuator and an output drive amplifier. Between the input and output series circuits is interposed a linearizer. In this linearizer, a splitter produces first and second signal portions, a first path comprises serially interconnected predistorter and third variable attenuator for distorting and adjusting the amplitude of the first signal portion, a second path comprises serially interconnected phase shifter and fourth variable attenuator for phase-shifting and adjusting the amplitude of the second signal portion, and a combiner combines the distorted and amplitude-adjusted first signal portion and the phase-shifted and amplitude-adjusted second signal portion to form a predistorted output signal applied to the output series circuit. A digital controller includes a processor for measuring the level of a temperature of operation of the power amplifier through an interface, and a look-up table for storing predistortion control parameters related to different levels of the temperature of operation. The processor is connected to the look-up table for selecting predistortion control parameters in relation to the measured temperature level, and for applying through a D/A converter and a signal conditioner the selected predistortion control parameters to the first, second, third and fourth variable attenuators and to the phase shifter in view of producing a predistorted output signal which cancels a distortion subsequently produced by the power amplifier.

Temperature compensated and digitally controlled amplitude and phase channel amplifier linearizer for multi-carrier amplification systems

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Montréal, Canada

Said Touimer