A Synthetic Wideband SAW Filter Using Parallel DMS

A novel wideband surface acoustic wave (SAW) bandpass filter with two parallel double-mode SAW (DMS) structures is proposed and studied in this paper. Each DMS has three IDT blocks and a pair of reflectors between the IDTs. This proposed structure has a new resonance point in-phase with the grating resonance point. It is suitable for designing a synthetic passband beyond the limit of the original electro-mechanical coupling coefficient (K
²
) leading to a high rectangle factor. The filter is fabricated on a standard 42° Y-X Lithium Tantalate (LiTa03) substrate. The measured −3 dB bandwidth range is 753-818MHz (8.27%). A function to characterize the bulk wave is also introduced for expanding the range of accuracy of the COM model.