| 摘要 |
PURPOSE:To improve operativity and precision by constituting parallel elements by combining input admittance elements of inputside roll screen type electrodes of surface acoustic wave filters and a capacitor. CONSTITUTION:Parallel elements are constituted by connecting input admittance elements of input-side roll screen type electrodes 2 of surface acoustic wave filters 1 and the capacitor 5 in parallel, so the electrostatic capacity value of each parallel elements is controlled by varying the electrostatic capacity value of the capacitor 5. Therefore, the inductance value of a coil 3 required to obtain a necessary cut off frequency and nominal impedance is varied by varying the number of the filters 1. Consequently, good operativity and high manufacture precision are obtained and the small-sized coil 3 is usable. |
