The optimizationg of low-loss SAW filter with high rectangle factor

High rectangle factor has been one of the most impressive characters of SAW filter, especially low-loss SAW filters used in recent years. Many experts dedicated to this kind of research and obtained some excellent results, many improvements were promoted as well. This paper starts form frequency dependent COM parameters extraction method, discussing the pitch-modulated IDTs and reflectors structure and in between shorted-grating structure, high rectangle factor, low-loss DMS can be easily designed by using COM model and global optimization algorithm. Some optimized results have been given in this paper; High precision Stepper and lift-off technology be used in order to realize these filters, the results are in accordance with theory simulation well, the most important is the yield of product has been greatly improved.