Patent ID: 7498905
Filing Date: 2009-03-03
Classification: H03H

Abstract:
1. A SAW filter comprising: a piezoelectric substrate, and a plurality of surface acoustic wave devices formed on one side of the piezoelectric substrate, each including a pair of opposite interdigitated electrodes formed by conductors and connecting electrodes formed by conductors and connected respectively to the interdigitated electrodes, wherein pattern portions formed by conductors provided on circumferences of the plurality of surface acoustic wave devices and conductor removing portions provided between the surface acoustic wave devices and the pattern portions are formed on the one side of the piezoelectric substrate, and wherein the shape of the surface acoustic wave devices is formed by the conductor removing portions, and the surface acoustic wave devices remain non-conductive with the pattern portions by the conductor removing portions; each of the conductor removing portions includes a shape removing portion for forming the shape of the surface acoustic wave devices and a lateral removing portion connected to the shape removing portion from a periphery including boundaries between the interdigitated electrodes and the connecting electrodes at both ends of one of the surface acoustic wave devices, the lateral removing portion extending toward a side edge of the piezoelectric substrate, and the pattern portion located at both sides of the surface acoustic wave device is separated into two portions by the lateral removing portion; and wherein the SAW filter is composed of a ladder filter in which the plurality of surface acoustic wave devices is connected in series to one another and a plurality of other surface acoustic wave devices is connected in parallel with respect to the plurality of surface acoustic wave devices connected in series, and the lateral removing portion is provided at both ends of at least one of the plurality of surface acoustic wave devices connected in series.