Acoustic wave device, filter, and duplexer

Acoustic wave device comprising:

• a piezoelectric substrate;
• a first Interdigital Transducer (IDT) located on the piezoelectric substrate and including electrode fingers and two bus bars,
• a second IDT located on the piezoelectric substrate, including electrode fingers and two bus bars, and connected in series to the first IDT;
• and
• a pair of reflectors that sandwiches only the first IDT and the second IDT, wherein
• the first IDT and the second IDT share a single common bus bar as a first bus bar of the two bus bars of the first IDT and a first bus bar of the two bus bars of the second IDT,
• the common bus bar has a width that is not more than two times and more than 0.3 times a wavelength of an acoustic wave propagating through the first IDT and the second IDT, and is a floating electrode,
• the common bus bar connects to no dummy electrode finger facing a tip of the electrode finger connected to a second bus bar of the two bus bars of the first IDT across a gap and no dummy electrode finger facing a tip of the electrode finger connected to a second bus bar of the two bus bars of the second IDT across a gap, and
• a line and space ratio of the electrode fingers included in the first IDT differs from a line and space ratio of the electrode fingers included in the second IDT.

A ladder-type filter comprising series resonators and parallel resonators, at least one of the series resonators and the parallel resonators including:

• a first Interdigital Transducer (IDT) including electrode fingers and two bus bars connected to the electrode fingers of the first IDT;
• and
• a second IDT including electrode fingers and two bus bars connected to the electrode fingers of the second IDT, and connected in series to the first IDT, wherein
• the first IDT and the second IDT share a single common bus bar as a first bus bar of the two bus bars of the first IDT and a first bus bar of the two bus bars of the second IDT,
• the common bus bar has a width that is not more than two times a wavelength of an acoustic wave propagating through the first IDT and the second IDT,
• the common bus bar connects to no dummy electrode finger facing a tip of the electrode finger connected to a second bus bar of the two bus bars of the first IDT across a gap and no dummy electrode finger facing a tip of the electrode finger connected to a second bus bar of the two bus bars of the second IDT across a gap, and
• a line and space ratio of the electrode fingers included in the first IDT differs from a line and space ratio of the electrode fingers included in the second IDT.