Acoustic wave device with multi-period arccosine apodization

A coupled resonator filter, comprising a plurality of acoustic resonators arranged in a length direction, wherein each of the acoustic resonators comprises:

• a piezoelectric layer;
• and
• a plurality of interdigital electrode structures over the piezoelectric layer, wherein each of the plurality of interdigital electrode structures comprises:
• in a width direction, a plurality of first electrode fingers extending from a first busbar towards a first apodization edge, and a plurality of second electrode fingers extending from a second busbar towards a second apodization edge, the plurality of first electrode fingers and the plurality of second electrode fingers interleaved with one another along a length direction, the length direction being different from the width direction, wherein:
• at least one of the first apodization edge or the second apodization edge follows a periodic arccosine apodization function over at least two adjacent electrode fingers of the plurality of first electrode fingers or the plurality of second electrode fingers, a number of periods of the at least one of the first apodization edge or the second apodization edge being at least 2;
• and
• a first distance between one of a first electrode finger or a second electrode finger and the respective periodic arccosine apodization function is less than or equal to a predetermined percentage between zero and 100% of an apodization amplitude of the periodic arccosine apodization function.