Multiparameter tuning of surface-acoustic-wave filters

An experimental methodology for tuning the frequency response of surface-acoustic-wave (SAW) filters after initial fabrication is demonstrated. The sensitivity of such a filter to perturbations in the length of individual electrodes of the interdigital transducer is determined from highly accurate swept-frequency measurements. Sensitivity measurements from several electrodes are then used to synthesize improved filter responses. Sensitivity measurements, measurement accuracy, and control of frequency-response sidelobes are demonstrated for devices fabricated on (YZ) lithium niobate. The tuning method provides predictions of improvement that closely match actual performance.<>