Coupling Matrix Approaches for the Synthesis of Acoustic Wave Multiport Functions

Acoustic wave (AW) synthesis methodologies have arisen increasingly popular among AW filter designers due to their effectiveness and precision. With the increasing complexity of carrier aggregation schemes, there is a necessity of developing synthesis methods for AW multiplexers. However, when pursuing the synthesis of a multiport network, numerical accuracy plays an important role to succeed with the synthesis process. Polynomial degrees as well as the number set of polynomial coefficients are, among others, important sources of error during the extraction of the circuital elements of the filter. Nonetheless, in this work is demonstrated that coupling matrix methodologies are the best choice when aiming to synthesize filtering functions with complex roots in their characteristic polynomials, which is the case of the channel polynomials of the multiport device. A B3Rx-B3Tx duplexer example is used as a vehicle to demonstrate the validity of the proposed approach.