Design for Acoustic Wave Multiplexers With Single Inductor Matching Network Using Frequency Response Fitting Method

Abstract

This study proposes a new acoustic wave (AW) multiplexer topology with a single-inductor matching network for carrier aggregation (CA) in the fifth-generation communication systems. To satisfy the desired specifications of all the multiplexer ports based on ladder-type filters, the frequency response fitting method (FRFM) is proposed to obtain the BVD parameters for each AW resonator. Using the proposed computer-aided method, a parameter solution can be obtained under practical design limitations, such as the selection of the piezoelectric material, properties of the manufacturing process, and used circuit topology. Furthermore, a measurement of a band 1 and 3 surface acoustic wave (SAW) multiplexer is set up to confirm the feasibility of the proposed FRFM. The designed SAW multiplexer based on the lithium tantalate with Euler angle (0, −38, 0), 42°YX-LiTaO ₃ , is arranged. The designed quadplexer achieves high selectively with a return loss (RL), stopband reflection, and isolation better than −12 dB, −43 dB, and −50 dB, respectively, in a $2.15\times2.65$ mm ² occupation. The measurement results confirm the feasibility of the multiplexer topology and the proposed FRFM. The approach is also extended to a quadplexer design with band 4 and 25 and a hexaplexer design with band 1, 3, and 7 for CA applications, demonstrating its flexibility and simplicity.