Phase linear ·flat wide band· low loss filters using new configuration of unidrectional up-chirp and down-chirp dispersive inter digital transducers

Dispersive transducers have sharp cut-off and flat wide band frequency characteristics. Also phase linear and very low loss characteristics are obtained by combining down-chirp and up-chirp unidirectional dispersive transducers (DUDIST and UUDIDT). We proposed the wide band filters combining DUDIDT and UUDIDT using the conventional UDT with the grating thin films. In this case, we could not obtained the low loss results. In this paper, the theoretical results of phase linear, flat wide band and low loss filters using combining new DUDIDT and UUDIDT are described. DUDIDT and UUDIDT are obtained by using new configuration of Dispersive IDT. The large unidirectinalities of DUDIDT and UUDIDT are obtained by using the change of the electrode width and thickness, and open and short -circuit electrode as the reflectors.