Effects of delay lines on surface acoustic wave resonator filters and their applications

The surface acoustic wave (SAW) resonator filters consisting of a pair of interdigital-electrode transducers can generate and transmit acoustic waves. By inserting a grating, we can improve the frequency response and lower the insertion loss; therefore appropriate design of the delay line will be very important. In this paper, we used the coupling-of-mode (COM) theory to model the frequency response of the SAW device and discuss the influence of the delay line on the frequency response. We found that the optimum delay line distance and the corresponding insertion loss is very small, which will be very helpful in designing corresponding SAW-coupled resonator filters.