Patent ID: 7701311

Claim:
An antenna duplexer, comprising: an antenna terminal; a transmission terminal; a receiving terminal; a transmission filter connected between the antenna terminal and the transmission terminal; and a receiving filter connected between the antenna terminal and the receiving terminal, wherein: the receiving terminal is a balanced type terminal, and the transmission terminal is an unbalanced type terminal; both the transmission filter and the receiving filter include at least one film bulk acoustic resonator serially connected to the antenna terminal, and both the transmission filter and the receiving filter include at least one film bulk acoustic resonator connected in parallel between the antenna terminal and ground; the receiving filter connected to the balanced type receiving terminal includes a ladder type filter connected between a longitudinal mode coupled surface acoustic wave filter and the antenna terminal; the ladder type filter of the receiving filter includes the at least one film bulk acoustic resonator serially connected to the antenna terminal and the at least one film bulk acoustic resonator connected in parallel between the antenna terminal and ground, one of the at least one film bulk acoustic resonator serially connected to the antenna terminal and included in the ladder type filter of the receiving filter being closest to the antenna terminal in relation to any other film bulk acoustic resonator included in the ladder type filter; a number of the film bulk acoustic resonators connected in parallel between the antenna terminal and ground is less than a number of the film bulk acoustic resonators serially connected to the antenna terminal; a passband of the transmission filter is lower than a passband of the receiving filter; and the transmission filter connected to the unbalanced type transmission terminal includes a ladder type filter.