Pulse or digital communications – Transmitters – Antinoise or distortion
Patent
1996-07-08
2000-08-22
Chin, Stephen
Pulse or digital communications
Transmitters
Antinoise or distortion
375296, 375297, 330149, H04K 102
Patent
active
061083852
ABSTRACT:
Signal processing to remove unwanted signal components of non-linear elements such as RF amplifiers in broadband wireless communications systems that exhibit unwanted intermodulation products. An information signal is processed to form a processed output signal, V.sub.od. A signal preprocessor includes a base modulator for modulating the information signal to form base modulated signals, a band modulator for modulating the base modulated signals to form an input signal, V.sub.i, a distortion processor for providing a predistortion signal V.sub.pd having selected predistortion terms of the Taylor series form [k.sub.1,(V.sub.i).sup.1, k.sub.2 (V.sub.i).sup.2, k.sub.3 (V.sub.i).sup.3, . . . ], and a broadband processor for combining the input signal V.sub.i and the predistortion signal V.sub.pd to form a predistorted signal V.sub.id with the selected predistortion terms of the Taylor series form [k.sub.1 (V.sub.i).sup.1, k.sub.2 (V.sub.i).sup.2, k.sub.3 (V.sub.i).sup.3, . . . ] having reduced amplitude. A non-linear element having a non-linear transfer function for processes the predistorted signal V.sub.id to form the output signal with the selected predistortion terms of the Taylor series form [k.sub.1 (V.sub.i).sup.1, k.sub.2 (V.sub.i).sup.2, k.sub.3 (V.sub.i).sup.3, . . . ] having reduced amplitude. Amplifiers achieve substantial improvements in efficiency, an increase of 40-80% of usable power, due to the reduction of intermodulation products. In particular, the third order products are reduced.
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Chin Stephen
Liu Shuwang
Lovejoy David E.
Silicon Wireless Limited
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