Investigation of misalignment in microwave multilayer filters

Studies have been conducted on edge-coupled bandpass filters as the component used to assess the performance of the multilayer circuits and fabrication error at various frequencies (5GHz and 25GHz). The outcomes of the work showed the performance benefits that accrue from the use of multilayer circuits, in terms of a significant improvement in bandwidth while maintaining the quality of the filter roll-off. An analysis of the fabrication errors provided useful guidelines for deciding the degree of alignment accuracy needed for a certain application, and presented data not previously reported in the literature. A particularly significant error that was quantified was that of skew between conductors on different layers, where it was found that a skew angle of only 0.1° resulted in very significant changes in bandwidth and insertion loss.