Validation and application of nonlinear elastic model to design triple-beat-free SAW duplexers

We have proposed the nonlinear elastic model for predicting the nonlinear responses of surface acoustic wave (SAW) duplexers, especially for the in-band 3rd order nonlinear distortion, the so-called `triple beat'. This paper validates the nonlinear elastic model by comparing the simulated triple beat responses to the measurements in several designs of SAW duplexers. The model precisely simulates the every measurement result with an accuracy as high as a few dB. This model is applied to design the highly linear SAW duplexers for 1.9 GHz Personal Communications Service (PCS). The developed SAW duplexer achieves the extremely high linearity of approximately -90 dBc in the triple beat test, which is 20 dB better than the conventional duplexer keeping the equivalent filter characteristics and same packaging size. To the best of our knowledge, this is the first PCS SAW duplexer which satisfies the triple beat specification required in CDMA2000.