Patent ID: 7039130
Filing Date: 2006-05-02
Classification: H04B,H04L

Abstract:
1. For use in a receiver having front-end circuitry for down-converting an RF signal to produce a raw in-phase (I) signal and a raw quadrature (Q) signal, said raw I signal and said raw Q signal each having M discrete signal levels defining an M×M constellation of raw (I,Q) input vectors, a phase tracking circuit for correcting a phase error rotation angle φ associated with said M×M constellation, said phase tracking circuit comprising: a phase rotation circuit capable of receiving said raw (I,Q) input vectors and rotating said raw (I,Q) input vectors by an expected correction angle to produce corrected (I*,Q*) vectors; a phase error calculation circuit capable of rotating each of said corrected (I*,Q*) vectors into the first quadrant of a rectangular coordinate system, converting said rotated (I*,Q*) vectors to polar coordinates, subtracting an angle associated with each of said converted (I*,Q*) vectors from 45 degrees to thereby produce a plurality to difference angles, and adding each of said difference angles to said expected correction angle to produce a plurality of estimated correction angle values; and an averaging circuit capable of calculating an average vector value from N of said plurality of estimated correction angle values, wherein said expected correction angle is derived from said average vector value.