Automatic computer-aided design of SAW filters using slanted finger interdigital transducers

Area of Science:

• Electrical Engineering
• Materials Science
• Acoustics

Background:

• Surface Acoustic Wave (SAW) filters are crucial components in modern electronics.
• Traditional apodized interdigital transducers (IDTs) have limitations in representing impulse responses directly.
• Slanted finger interdigital transducers (SFITs) offer potential for wideband applications but require novel design approaches.

Purpose of the Study:

• To develop a design procedure for SAW filters utilizing SFITs.
• To enable the creation of mid-band and wideband SFIT filters.
• To automate the design process for SFIT filters and their corresponding photomasks.

Main Methods:

• A frequency-domain, building-block approach for SFIT design.
• Implementation of withdrawal weighting for stop-band responses.
• Application of aperture and distance weighting for pass-band amplitude and phase responses, respectively.
• Development of an automatic computer-aided design (CAD) tool.

Main Results:

• A functional CAD tool for SFIT filter design has been successfully developed.
• The design procedure allows for automatic generation of SFIT patterns for photomasks.
• A 15% relative bandwidth SFIT filter was designed and fabricated on a LiTaO(3) substrate.

Conclusions:

• The described design procedure and CAD tool effectively enable the creation of SFIT SAW filters.
• SFITs are suitable for wideband applications, overcoming limitations of traditional IDTs.
• The automated design process facilitates the efficient development of high-performance SAW filters.