Correction of i / q inequalities in a quadrature - transmitter - receiver

摘要

The underlying invention generally relates to the field of coherent modulator architectures for the processing of modulated RF signals of digital communication systems, especially to a processing unit realizing an effective I/Q imbalance correction for high-level modulation schemes, e.g. 16-QAM or 64-QAM, under the coexistence of a carrier frequency error (Δf_RF).;According to one embodiment of the underlying invention, an I/Q modulator of a quadrature transmitter comprising a processing unit (302) for correcting the amplitude and phase of the I and Q signals by calculating calibration coefficients (h(M)) is applied, wherein the processing unit (302) is specially designed to carry out the following steps in order to calculate said calibration coefficients (h(M)): a) using a number of M signal samples in order to calculate initial calibration coefficients (hk(M)), wherein M is an integer value which is larger than 1, and b) calculating averaged calibration coefficients (h(M)) by averaging a plurality of said initial calibration coefficients (hk(M)) obtained by repeating step a) for a limited number of K repetitions, wherein K denotes an integer larger than 1. The averaged calibration coefficients (h(M)) are then used to correct the I and Q imbalance.