Motorola Corporation

Andrew Corporation

Paul S Everline

Thomas A Bachman, Ii

Paul E White

Robert W Kooker

Robert Snyder

Leonard Sarver

James C Baker

Mark G Obermann

Theodore F Longshore

David M January

Christopher G Rittler

William P DeClerk

William H Balacky

Philip Shenenberger

A feed forward power amplifier system and method identify active channels across a frequency band to suppress unwanted intermodulation distortion (IMD) products in a communications signal such as a single- or multi-carrier communications signal. A scanning receiver identifies at least one active channel in a frequency band, and identifies at least one portion of the frequency band likely to include IMD products based upon the identified active channel(s). Based upon the identified portion of the frequency band, IMD products are suppressed from the communications signal, e.g., by controlling the magnitude and/or phase of a suppression signal mixed with the communications signal.

Scanning receiver for use in power amplifier linearization

A power amplifier system and method for locating carrier frequencies across a frequency band, identifying the modulation format of each carrier, and locating and suppressing undesired intermodulation distortion (IMD) products generated by the power amplifier. The system includes an amplifier for amplifying RF carrier signals in a main signal path, a variable phase shifter and variable attenuator on a feed forward path, and a tunable receiver that digitizes a portion of the frequency band to baseband. The tunable receiver includes a tunable voltage controlled oscillator which provides an oscillating frequency to a mixer and is phase-locked to a highly stable reference oscillator. The mixer downconverts a desired RF based on the oscillating frequency to IF. A filter passes only a selected portion of the IF signals, and the filter has a passband sufficient to discern both narrowband and wideband carriers and their associated IMD products. Based on the locations of the carrier frequencies, a processing unit determines the IMD locations of the carrier frequencies, determines the IMD locations, and adjusts the variable phase shifter and variable attenuator on the feed forward path until the IMD products in the main signal path are suppressed below a desired threshold.

Digital baseband receiver in a multi-carrier power amplifier

An amplifier circuit (100) for use in a radio frequency system. The circuit is comprised of a first amplifier (22) having a first input (20) receiving a first signal (16) and a first output (24). A first coupler (18) samples the first input (20) of the first amplifier (22) and a second coupler (26) samples the first output (24) of the first amplifier (22). A third coupler (36) then compares an output of the second coupler (28) and an output of the first coupler (34), producing an error signal (38) which is substantially indicative of the difference between the first input (20) and the first output (24). A fourth coupler (44) combines the error signal (38) with a second signal (48) to produce a composite signal (50), the second signal (48) at least partially correlated with the first signal (16) received by the first input (20) of the first amplifier. A second amplifier (52) is responsive to the composite signal (50) and produces a second output (54).

Amplifier circuit and method of controlling an amplifier for use in a

A system for facilitating link continuity and prompt supervisory control in a communication system with discontinuous transmissions comprising varying the carrier power in a first communication unit and varying frequency deviation of a modulating signal to provide a continuous signal detectable by a second communication unit, where continuous monitoring at the second communication unit allows for rapid detection and reaction to received supervisory control signals through the use of continually comparing the received supervisory signal to an expected signal and qualifier signal to enhance the reaction time of the second communication unit.

Discontinuous transmission muting/unmuting system with link continuity

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Schaumburg, IL, United States of America

Paul S Everline