A research conducted by Takashi Ozaki et al. was published in Communications Physics.
With the widespread adoption of 5G and IoT technologies, smartphones and IoT devices are increasingly required to support a wide range of wireless communication standards. RF, or radio-frequency, filters play an important role in selecting desired radio signals while suppressing unwanted ones. In addition to being compact, these filters are expected to flexibly adjust the range of frequencies they allow to pass. However, conventional high-performance RF filters often require multiple resonators and many tuning elements, which can increase device size and design complexity.
In this study, we proposed a new RF filter approach that uses multiple vibration modes within a single MEMS mechanical resonator as if they were multiple resonators arranged in a line. By applying AC signals matched to the frequency differences between vibration modes, we artificially coupled different modes and created a virtual lattice along the frequency direction. By arranging the strengths of these couplings in an alternating pattern, a special state known as a topological edge state emerges and becomes localized at the ends of the virtual lattice. Numerical analysis showed that this state enables the filter to selectively transmit signals near a specific frequency. The study also showed that the transmission bandwidth can be continuously adjusted by changing the ratio of the AC signal amplitudes.
This technology could provide a pathway toward compact wireless communication devices that can flexibly accommodate a wide range of frequency bands while reducing the number of resonators and tuning parameters required.
Title: Electrically Reconfigurable Topological RF Filter Utilizing a Synthetic Frequency Dimension in a Single Mechanical Resonator
Authors: Ozaki, T., Ohta, N., Ma, J., Fujiyoshi, M.
Journal Name: Communications Physics
Published: April 09, 2026