A digital method for the correction of I/Q phase errors in complex sub-sampling mixers

Complex sub-sampling mixers are used in various kinds of image rejection receiver. The image rejection performance of these receivers is mainly limited by I/Q phase error. A digital calibration technique is proposed in this paper to correct this error. The phase error is measured by a statistical method with a local test signal, and is corrected in the baseband digital domain. With this method, the image rejection performance can be improved as much as 20 dB as indicated by high level simulation results.