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:
Apr. 21, 1992
Filed:
Jan. 09, 1990
Georges Karam, Paris, FR;
Hikmet Sari, Creteil, FR;
U.S. Philips Corporation, New York, NY (US);
Abstract
An adaptive predistortion circuit for a digital transmission system includes a predistortion circuit (52.sub.1, 52.sub.2, 52.sub.3) for predistorting the input data before they pass through a modulator (56) and then through an amplifier (57), and an adaptation circuit (61.sub.1, 61.sub.2, 61.sub.3) for continuously adapting the predistortion circuit to the stream of input data in response to a demodulation of the stream of transmitted data. The predistortion circuit further includes an encoder (51) which, on a first path, in response to digital data a.sub.k, generates digital data b.sub.k which leave a first predistortion circuit (52.sub.1) in a predistorted manner in-phase with the symbol clock, on a second path, digital data c.sub.k which leave a second distortion circuit (52.sub.2) in a predistorted manner phase-shifted by T/3 relative to the symbol clock and on a third path, digital data d.sub.k which leave a third predistortion circuit (52.sub.3) in a predistorted manner phase-shifted by 2T/3 relative to the symbol clock. The signals b.sub.k, c.sub. k and d.sub.k are obtained by means of a polynomial encoding. The encoding may be performed by shift registers (62.sub.1 . . . 62.sub.I) addressing a memory (63) or, by a transversal filter (71.sub.1, 71.sub.2, 71.sub.3). It may also be obtained by means of an analog transmission filter (81) followed by samplers (81.sub.1, 82.sub.2, 82.sub.3).