Transversely-excited film bulk acoustic resonator matrix filters with split die sub-filters

A method of forming a radio frequency filter, comprising:

• connecting a first sub-filter and a second sub-filter in parallel between a first port and a second port, wherein connecting the first sub-filter comprises:
• bonding a first piezoelectric plate to a first substrate first portions of the first piezoelectric plate forming a first plurality of diaphragms over respective first cavities;
• and
• forming a first conductor pattern on the first piezoelectric plate, the first conductor pattern including a first plurality of interdigital transducers (IDTs) of a first respective plurality of resonators, first interleaved fingers of each IDT on a first respective diaphragm of the first plurality of diaphragms,
• wherein connecting the second sub-filters comprises:
• bonding a second piezoelectric to a second substrate second portions of the second piezoelectric plate forming a second plurality of diaphragms over respective second cavities;
• and
• forming a second conductor pattern on the first piezoelectric plate, the second conductor pattern including a second plurality of interdigital transducers (IDTs) of a second respective plurality of resonators, second interleaved fingers of each IDT on a second respective diaphragm of the second plurality of diaphragms,
• wherein a thickness of the first portions of the first piezoelectric plate is thicker than a thickness of the second portions of the second piezoelectric plate, and
• wherein the first substrate is different than the second substrate.

A method of forming radio frequency filter, comprising:

• connecting a first sub-filter, a second sub-filter and a third sub-filter in parallel between a first port and a second port, wherein connecting each of the first, second and third sub-filters comprises:
• bonding at least one piezoelectric plate to at least one substrate, portions of the at least one piezoelectric plate forming a plurality of diaphragms over respective cavities;
• and
• forming a conductor pattern on only one surface of the at least one piezoelectric plate and not an opposing surface of the piezoelectric plate, the conductor pattern including a plurality of interdigital transducers (IDTs) of a respective plurality of resonators, interleaved fingers of each IDT disposed on a respective diaphragm of the plurality of diaphragms;
• wherein a thickness of the portion of the at least one piezoelectric plate of the first sub-filter is different from a thickness of the respective portions of the at least one piezoelectric plate of the second and third sub-filter, and
• wherein the thickness of the portion of the at least one piezoelectric plate of the second sub-filter is different from the thickness of the portion of the at least one piezoelectric plate of the third sub-filter.