Wideband SAW filters using cascaded unidirectional transducers

An improved cascaded UDT structure has been proposed to achieve wideband performances. In order to confirm the prediction, simulations and experiments are applied. We select the equivalent circuit model and circuit composition procedure as a simulation technique. The predictions are verified by the simulations and the experiments. It is no restriction for bandwidth of cascaded transfer function according to the simulation results. The structure is applied to a wideband RF filter which consists of IDTs for the purpose of monitoring. Two times wider bandwidth of the filter than the conventional one is obtained and the transfer functions for forward, backward and through transducer are found to be unidirectional