Mathematical analysis of inter-band intermodulation for concurrent dual-band mixers

Recently concurrent dual-band receivers are being investigated to help improve data rates and ease roaming across different network standards. Traditionally, nonlinear behavior has been confined to two-tone tests where the tone spacing is relatively small. In concurrent dual-band systems, however, two bands must be received simultaneously with an arbitrary spacing between the bands. In this paper, the intermodulation issues between bands and between the signals within a given band are analyzed. It is found that there are certain band spacings that must be avoided because of significant intermodulation distortion. Based on this analysis, a frequency plan to avoid inter-band nonlinear distortion is proposed. These results are then verified with Matlab simulations.