Acoustic surface wave filter device

A surface acoustic wave filter device having a Ping Heng to unbalanced conversion function, the device of different input / output impedance of the pass band and a good balance. The surface acoustic wave filter having a Ping Heng to unbalanced conversion function, in this device, the second surface acoustic wave filter element input / output IDT of the first surface acoustic wave filter element than the spacing of the input / output IDT, half wavelength spacing wave loud, so that the phase inverter, wherein the plurality of electrostatic capacitance values ​​of the total IDT of the second surface acoustic wave filter element is greater than the plurality of first surface acoustic wave filter elements IDT total capacitance value.