ACOUSTIC WAVE ELEMENT, BRANCHING FILTER AND COMMUNICATION MODULE

摘要

SAW element has a substrate; an IDT having a first comb-shaped electrode and a second comb-shaped electrode located on an upper surface of the substrate; and a capacitance element located on the upper surface of the substrate. The capacitance element has a first counter electrode connected to the first comb-shaped electrode and a second counter electrode connected to the second comb-shaped electrode and facing the first counter electrode across a third gaps. The direction from the first counter electrode through the third gaps toward the second counter electrode is a reverse direction from the direction from the first comb-shaped electrode through the gaps toward the second comb-shaped electrode. If it is assumed that the gap and width of the gap are di and wi, and the gap and width of the third gap are Dj and Wj, the following formula holds:;0<Σ(Wj/Dj2)<2Σ(wi/di2)

主权项

1. An acoustic wave element comprising:
a piezoelectric substrate, an IDT comprising a first comb-shaped electrode and a second comb-shaped electrode which are located on an upper surface of the piezoelectric substrate, and a single capacitance element which is located on the upper surface of the piezoelectric substrate and is electrically connected to the IDT, wherein the first comb-shaped electrode comprises
a first bus bar anda plurality of first electrode fingers extending from the first bus bar, the second comb-shaped electrode comprises
a second bus bar anda plurality of second electrode fingers extending from the second bus bar, in the first comb-shaped electrode and the second comb-shaped electrode, the plurality of first electrode fingers and the plurality of second electrode fingers mesh with each other, the first electrode fingers have tips facing the second comb-shaped electrode across first gaps in their extending direction, the second electrode fingers have tips facing the first comb-shaped electrode across second gaps in their extending direction, the capacitance element comprises
a first counter electrode which is connected to the first comb-shaped electrode anda second counter electrode which is connected to the second comb-shaped electrode and faces the first counter electrode across a third gap, the direction from the first counter electrode through the third gap toward the second counter electrode is a reverse direction from the direction from the first comb-shaped electrode through the first gaps toward the second comb-shaped electrode and from the direction from the first comb-shaped electrode through the second gaps toward the second comb-shaped electrode, and a length D and width L of the third gap satisfy the following formula (A) where the total number of the first gaps and the second gaps is n (n≧2), and lengths and widths of the i-th first gap and second gap among the first gaps and the second gaps which are counted in order from one end of the IDT are di and wi (1≦i≦n):0