| 摘要 |
A filter structure (900, 1300, 1400, 1610) comprises a filter section (900) having at least two branches (901, 902) connected in parallel. A first branch (901) of said at least two branches comprises a first plurality (921, 701) of piezoelectric resonators connected in series, and a second branch (902) of said at least two branches comprises a second plurality (922, 702) of piezoelectric resonators and phase shifting means (910) connected in series. The phase shifting means are arranged to provide a phase shift of substantially 180 degrees.
|
