An exceptional video recently landed deep diving into how structual formations like this were used to miniaturize RF notch filters[0], really incredible enginee

An exceptional video recently landed deep diving into how structual formations like this were used to miniaturize RF notch filters[0], really incredible engineering. The acronym naming the input and output terminals, IDT, means interdigitated tranducer. The features are created with semiconductor lithography onto a piezoelectric substrate. This type of filter is known as a SAW, surface acoustic wave filter. The reflectors on the end make this configuration considered a SAW resonator. Another form of this filter has the input on the top while the output is on the bottom which can offer much higher frequency filters, these are known as BAW filters, bulk acoustic wave. Like many other verticals, shrinking the spacing in the IDTs is critical for raising its frequency, and so some advancements have been and are constrained by lithography capabilities. BAWs, and later FBARs, were actually one method used to circumvent this limitation, it then becomes limited by deposition thickness. The complexity between SAW and BAW filter also vary wildly, while a SAW can be made with 1-3 masks, BAW filters require 9-13. [0] https://www.youtube.com/watch?v=L8jmHtfVmPY https://www.youtube.com/watch?v=L8jmHtfVmPY