Adaptive Canceller Limitations Caused by I,Q Mismatch Errors.
NAVAL RESEARCH LAB WASHINGTON DC
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The effects of I and Q phase, amplitude, and low pass filter LPF errors on adaptive cancellers are investigated. I,Q errors occur because of errors in the synthesis process of the mixers and LPFs designed to be identical for each input channel. These I,Q errors among the channels result in cancellation degradation. Tapped delay line transversal filters have been proposed as a way to compensate for these errors and thus improve cancellation performance. However, it is shown that if there is any LPF mismatch, then transversal filter has a small effect on improving canceller performance. The method of individual I,Q adaptive transversal filter weighting is suggested as a means of eliminating the phase and amplitude errors and making the canceller performance responsive to transversal filter compensation. In addition, the cancellation performance of cascaded mismatched IF and I,Q filters is briefly considered. Keywords Adaptive filter Radar Adaptive cancellation. JHD
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