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High-Performance, Acoustically Coupled Filter for Reconfigurable RF Front Ends

Al-Sc-N Films Enable Local Tuning to Filter Bandwidths 3 to 5 Times Larger Than State-of-the-Art

This monolithic, wideband RF filter easily reconfigures for different bandwidths and performs better than many electrically coupled RF filters. Radiofrequency filters enable numerous electronic devices to communicate via wireless signals and prevent undesired signals from creating background noise and interference. Projections for the market for tunable RF filters show growth from $89 million in 2020 to $148 million by 2025. Monolithic RF filters, which operate with only the integrated circuit processes of a single silicon chip, are beneficial for designing and manufacturing electronics and minimizing device sizes. Acoustic coupling allows for this monolithic integration, but available acoustically coupled designs do not perform as well as electrically coupled designs, having smaller bandwidths and larger insertion loss.


Researchers at the University of Florida have developed an acoustically coupled RF filter that uses aluminum-scandium-nitride film to improve performance. The film’s greater electromechanical coupling gives the filter a bandwidth and tuning range larger than what available acoustically coupled RF filters have achieved.




High-performance, monolithic RF filter for electronic devices that allows dynamic reconfiguration of a large bandwidth and frequency range, useful for emerging multi-band 5G wireless systems



  • Employs better electromechanical coupling, filtering bandwidths 3 to 5 times larger than allowed with available filters
  • Reduces insertion loss, enhancing performance to strengthen signals
  • Allows bandwidth tuning via a local DC bias, providing agile reconfigurability necessary for multi-band devices
  • Enables monolithic high-performance RF filters, allowing for more compact devices easier to design and fabricate


This high-performance, acoustically coupled RF filter has a monolithic design suitable for use in the reconfigurable RF front ends of multi-band wireless systems. The acoustically coupled filter uses ferroelectric aluminum-scandium-nitride film that has strong electromechanical properties to allow for large bandwidth reconfigurability within the 2.3GHz wideband. Using ferroelectric Al-Sc-N film with 30 percent Sc content facilitates dynamic reconfiguration of the filter’s bandwidth and frequency using a DC voltage.

Patent Information: