The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 13, 1999
Filed:
May. 05, 1997
Robert Richard Leyendecker, Blaine, WA (US);
Jay Jui-Chieh Chen, Vancouver, CA;
Armando Cova Garrido, Vancouver, CA;
Yan Guo, Burnaby, CA;
Vladimir Pavlovic, Vancouver, CA;
Claudio Gustavo Rey, Port Moody, CA;
Desmond Wai Yan, Vancouver, CA;
Glenayre Electronics, Inc., Charlotte, NC (US);
Abstract
A system for linearly transmitting an amplified output signal using predistortion whereby a straight inverse modeling scheme is used to more easily and accurately determine the inverse of the distortion caused by a power amplifier of a RF transmitter. The 'inverse' of the power amplifier is directly modeled by considering the power amplifier as a signal processing block with the input and output ports reversed. As a result, the computationally intensive inversion required by conventional schemes is avoided. The predistorter system stores complex coefficients in a predistorter LUT, which are then used as the tap weights of a digital filter implementing the predistorter. The predistortion is done by a non-linear filter which incorporates both instantaneous and average envelope power or magnitude effects. The predistortion LUT is addressed as a function of the instantaneous envelope power or magnitude and past power or magnitude envelopes. This scheme takes into account the instantaneous envelope power or magnitude of the current sample and a profile of the envelope power or magnitude of previous samples to accurately compensate for modulation envelope memory effects of the power amplifier. The past powers or magnitudes provide an indication of the trajectory of the power or magnitude leading to the current power or magnitude, which enables the predistorter to more accurately compensate for the power amplifier distortion. The predistorter LUT is updated with values that are indexed as a function of the powers or magnitudes of past samples and the power or magnitude of the current sample.