Lucent Technologies Inc.

John Rolland Welch

Israel Amir

Michael S Heutmaker

A method for correcting the phase and amplitude imbalance of a quadrature modulated RF signal requires that errors be induced in both amplitude, &rgr;, and in phase &phgr; in at least three different combinations in order to determine the appropriate correction value for amplitude and phase offsets &Dgr; and &thgr; . According to a first embodiment the same &rgr; and &phgr; offsets applied in three different combinations to determine the necessary &Dgr; and &thgr; corrections. According to a second embodiment, a fourth measurement is made in order to determine an unknown control scale factor for balance adjustments.

Method and system for correcting phase and amplitude imbalances of a quadrature modulated RF signal

The DC offset error of a quadrature modulated RF signal is corrected by introducing a specific trial offset correction value, D, into the DC offset correction circuits 3, 4 or 5 times, by measuring the carrier power resulting from each trial introduction, and by using the information to determine the DC offset correction components, I and Q . According to an ideal case first embodiment, specific offset D is employed in three different measurement combinations to determine the correction factors I and Q . According to an alternative embodiment, a fourth offset correction measurement, needed to estimate a single offset control scale factor, is used to account for an unknown power scale factor A. According to a second alternative embodiment, five offset correction measurements are used to account for separate offset control scale factors for the I and Q channels.

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Mt. Laurel, NJ, United States of America

John Rolland Welch