Duplexer incorporating thin-film bulk acoustic resonators (FBARs)

摘要

A band-pass filter comprising shunt elements and series elements in which the series elements and the shunt elements are connected to form a ladder circuit, and each of the elements includes a film bulk acoustic resonator (FBAR). An FBAR-based duplexer comprises a first port, a second port, a third port, a first FBAR-based band-pass filter as just described connected between the first port and the third port and a series circuit connected between the second port and the third port. The series circuit includes a 90 DEG phase shifter in series with a second FBAR-based band-pass filter as just described. <IMAGE>