Pulse or digital communications – Transmitters – Antinoise or distortion
Patent
1997-05-05
1999-07-13
Chin, Stephen
Pulse or digital communications
Transmitters
Antinoise or distortion
455126, H04L 2549
Patent
active
059237120
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.
REFERENCES:
patent: 4291277 (1981-09-01), Davis et al.
patent: 4462001 (1984-07-01), Girard
patent: 5049832 (1991-09-01), Cavers
patent: 5699383 (1997-12-01), Ichiyoshi
patent: 5732333 (1998-03-01), Cox et al.
patent: 5748678 (1998-05-01), Valentine et al.
Chen Jay Jui-Chieh
Garrido Armando Cova
Guo Yan
Leyendecker Robert Richard
Pavlovic Vladimir
Chin Stephen
Deppe Betsy L.
Glenayre Electronics, Inc.
LandOfFree
Method and apparatus for linear transmission by direct inverse m does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for linear transmission by direct inverse m, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for linear transmission by direct inverse m will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2284055