The effect of reconstruction filters on direct upconversion in a multichannel environment

The effect of reconstruction filters on direct upconversion is analyzed in a multichannel environment. It is shown that the reconstruction filters cause gain and phase imbalances to be frequency dependent, a significant issue when considering the stringent adjacent channel interference (ACI) requirements for radio communication systems. The paper introduces an adaptive compensation technique as a means of overcoming these frequency dependent imbalances. Additionally the error vector between the mismatched filters is shown to be directly related to the amount of sideband rejection. This analysis is then used to develop a methodology for analysing the performance of the novel compensation technique with respect to the mismatched filters. Analysis of the classical all-pole filter algorithms reveal the sensitivity of direct upconversion in a multichannel environment to filter order, type, percentage mismatch and differing ACI level