A design automation system, called SAWCOM, has been developed for the noninteractive design and analysis of SAW (surface acoustic wave) filters using bidirectional transducers. Such a system increases productivity by reducing filter design time while increasing design accuracy. The SAWCOM system takes as input a high-level performance specification of the SAW filter to be designed, as well as parameters pertaining to substrate availability and fabrication capabilities, and then begins a synthesis-analysis-verification cycle which continues until all design alternatives that meet the specifications are found, within the constraints of the SAWCOM system. To determine the filter’s design parameters, the system uses a set of design rules implemented in the PROLOG language. The system’s design rule base relates design and analysis parameters, which include parameters such as substrate choice and other material parameters, structural organization parameters such as the weighting technique, and the transducer parameters such as the sampling rate. The design rules provide an implementation of the necessary design curves and relationships and allow for the possibility of an exhaustive check of design solutions. The SAW filter parameter relationships included in the design rules allow the design automation system to iteratively correct in a closed loop design process for nonideal device behavior, such as passband distortion due to electrode charge effects and electrical equivalent circuit model effects.
This work was funded in part by the Florida High Technology and Industry Council.