Dual-Band Surface Acoustic Wave Filter Based on Parallel Connected Resonators

This paper proposes a novel surface acoustic waves (SAW) dual-band bandpass filter (DB-BPF) topology. Firstly, the proposed dual-resonance unit is constructed by connecting interdigital transducers (IDTs) in parallel with different resonant frequencies. Then, by replacing the single IDT in the standalone ladder topology with the proposed dual-resonance unit, a dualpassband response can be achieved. This design method eliminates the need for additional matching components. Moreover, since the overall capacitance of the dual-resonance unit is the sum of the static capacitance of each IDT, the required area of each IDT is reduced, enabling filter miniaturization. Finally, grounding inductors and a bridging capacitor are designed to improve the stopband rejection on both sides of each passband. A DB-BPF was fabricated and tested, demonstrating excellent performance with good agreement between simulation and measurement results.