Surface acoustic wave or SAW filter of small length based on the central frequency of the filter such as for multimedia applications

摘要

The surface wave filter has a central frequency. It has first and second converters arranged in an acoustic track. The second converter is formed as a broadband recursive interdigital converter. This converter has elementary cells of a cell type characterized by a given finger connection sequence and each having a stimulation and/or reflex center. At the central frequency of the filter, the phase difference between at least one stimulation center and a reflex center in the second converter differs from a value equal to (2n+1)pi/4. The length of the elementary cells is constant with respect to the central frequency of the filter.