论文信息 - Low-Loss SAW Filter Using Single-Phase IDTs and No External Tuning

Low-Loss SAW Filter Using Single-Phase IDTs and No External Tuning

Currently available techniques for implementing SAW filters with low insertion loss generally require multi-layer fabrication and/or complex external tuning and matching networks, with corresponding cost and size penalties. Here we report a new type of low-loss SAW filter which uses single level f abrication and which is naturally matched to 5011 and so requires no external components. The IDTs are d isplaced laterally (rather than the usual longitudinal arrangement), and SAW is transmitted between these IDTs by two reflecting multistrip couplers (RMSC) of a novel d esign. Most of the selectivity is provided by the RMSCs. The IDTs perform some filtering but the main design consideration was to achieve a natural 50R real impedance. Results are presented for the experimental and theoretical charactrrisation of many designs of RMSC on 128O YX lithium niobate and the responses of filters with fractional bandwidths of about 1% are shown.

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