A multi-IDT input tunable surface acoustic wave filter

摘要

Tunable surface acoustic wave (SAW) filters (TSF) have been widelynused in the wireless telecommunication systems. A prototype of multi-IDTn(interdigital transducer) input TSF has been developed. The devicenconsists of 11 IDTs paralleled in the SAW propagation path. DifferentnSAW filter configurations are realized by selecting or combining variousnIDTs, resulting in the tunability of both center frequency and 3 dBnbandwidth. The center frequencies of the SAW filter range from 126.8 ton199.1 MHz; the 3 dB bandwidths range from 15.2 to 58.9 MHz. Impedancenweighting methods have been applied. The passband ripple has beennreduced from 6.44 to 1.37 dB after resistance weighting