Patent ID: 6885260
Filing Date: 2005-04-26
Classification: H03H,H04B

Abstract:
1. A duplexer comprising: a transmission port, reception port, and transmission/reception port; a transmission band filter which is connected between the transmission port and transmission/reception port and which includes a first ladder-type circuit including a first series element constituted of a film bulk acoustic resonator and a first shunt element constituted of a film bulk acoustic resonator and which has a transmission frequency pass band; and a reception band filter which is connected between the reception port and transmission/reception port and which includes a second ladder-type circuit including a second series element constituted of a film bulk acoustic resonator and a second shunt element constituted of a film bulk acoustic resonator and which has a reception frequency pass band not overlapped with the transmission frequency pass band, wherein at least one film bulk acoustic resonator for adjustment is connected between the port for transmission/reception and the first and second shunt elements, and a resonance frequency of the film bulk acoustic resonator for adjustment is set between the transmission frequency pass band and the reception frequency pass band.