Patent ID: 7236067
Filing Date: 2007-06-26
Classification: H03H

Abstract:
1. A surface acoustic wave filter comprising: a piezoelectric substrate; an input comb electrode arranged on said piezoelectric substrate and formed from at least one input finger electrode and at least one first common finger electrode, the input finger electrode alternating with the first common finger electrode, the input finger electrode receiving an input signal, the first common finger electrode being connected to ground; and an output comb electrode arranged on said piezoelectric substrate and formed from at least one output finger electrode and at least one second common finger electrode, the output finger electrode alternating with the second common finger electrode, the output finger electrode providing an output signal, the second common finger electrode being connected to ground, wherein said surface acoustic wave filter is a longitudinally coupled mode surface acoustic filter and includes said input comb electrode and said output comb electrode disposed within a single propagation path in which a surface acoustic wave propagates, said input comb electrode has a plurality of electrode fingers pitches, said output comb electrode has a plurality of electrode fingers pitches, an electrode fingers pitch having the most pairs of electrode fingers of said input comb electrode and an electrode fingers pitch having the most pairs of electrode fingers of said output comb electrode are different from each other, the electrode fingers pitch having the most pairs of electrode fingers of said input comb electrode is larger than at least one of the plurality of electrode fingers pitches of said input comb electrode, and said electrode fingers pitch having the most pairs of electrode fingers of said output comb electrode is larger than at least one of the plurality of electrode fingers pitches of said output comb electrode.