Parametric Synthesis of Single-Stage Lattice-Type Acoustic Wave Filters and Extended Multi-Stage Design.
Journal
Micromachines
Journal Volume
15
Journal Issue
9
ISSN
2072-666X
Date Issued
2024-08-26
Author(s)
Tseng, Wei-Hsien
Abstract
This study proposes a single-stage lattice-type acoustic filter using an analytical solution method for either a narrow passband filter or a wider passband filter using two kinds of parameter assignments in the Butterworth-Van Dyke (BVD) model. To achieve the goal of a large bandwidth or high return loss, two first-order all-pass conditions are used. For multi-stage lattice-type filters, the cost function is defined and design parameters are extracted by using pattern search, while the initial values are provided through single-stage design to shorten optimization time and allow convergence to a better solution. This method provides the S-parameter frequency response for the filter on the YX 42° cut angle of lithium tantalate (electromechanical coupling coefficient of about 6%) that can meet the system specifications as much as possible. Finally, the three-stage lattice-type was applied to various 5G bands with a fractional bandwidth of 2-5%, resulting in a passband return loss of 10 dB and an out-of-band rejection of 40 dB or more.
Subjects
BVD model
Chebyshev response
acoustic filter
lattice topology
optimization method
parametric analysis
wideband
SDGs
Type
journal article