In recent years, as wireless communication devices such as cell phones are upgraded, a Surface Acoustic Wave (SAW) device as a component is required to have a function of converting the unbalanced signal to the balanced signal, that is, the balun function. The balun function is achieved by connecting two SAW filters in parallel between an unbalanced terminal and two balanced terminals. An in-band insertion loss is reduced by making the number of electrode fingers of an InterDigital Transducer (IDT) which constructs the SAW filter different between filters. WO 2006/087875 (Document 1) discloses such SAW device.
In the SAW device disclosed in Document 1, both numbers of electrode fingers of IDTs constructing two SAW filters are an even number, or an odd number. In this case, a notch may be generated in the pass band, and an insertion loss may be deteriorated.
USPTO Backgrounds
USPTO Backgrounds