Pulse or digital communications – Transmitters – Antinoise or distortion
Reexamination Certificate
2007-05-08
2007-05-08
Kim, Kevin (Department: 2611)
Pulse or digital communications
Transmitters
Antinoise or distortion
C375S284000, C375S285000
Reexamination Certificate
active
10603798
ABSTRACT:
This invention provides a technique and an architecture to pre-distort signals such that when the signals are amplified, the non-linear distortions of the amplifier chain are opposite that of the pre-distortion thus yielding a distortion free or nearly distortion free signal at the output of the amplifier chain. This invention provides for a low power application by using a LUT predistortion that is performed on a composite real signal (I and Q combined) such that the size of the LUTs required is reduced to a very small size. In this invention, the I and Q input signals are digitally modulation with quadrature digital sinusoidal signals and then combined to create the real composite signal at a digital IF. The real signal is then pre-distorted to compensate for AM/AM distortion first and then for AM/PM distortion. The pre-distorted signal is then digitally decomposed back in to I and Q samples for conversion to analog and up conversion to RF. The non-pre-distorted real signal is sampled and compared with a sample of the post amplified signal and the non-linear update algorithm is updated to compensate for the variation of non-linear distortion as a function of time and temperature. The architecture and techniques described herein provide for a low power and low memory implementation that can be used in mobile applications such as cell phones and Personal Data Devices (PDAs).
REFERENCES:
patent: 6785342 (2004-08-01), Isaksen et al.
patent: 6909756 (2005-06-01), Nakajima
patent: 6985704 (2006-01-01), Yang et al.
patent: 2002/0034260 (2002-03-01), Kim
patent: 2002/0136324 (2002-09-01), Nagasaka
patent: 2003/0058959 (2003-03-01), Rafie et al.
patent: 2003/0179830 (2003-09-01), Eidson et al.
Kim Kevin
Smith Francis J.
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