Ultra-compact/low-Loss DPX with reflector-Less SAW Resonator

Miniaturization and loss reduction of surface acoustic wave (SAW) devices are critical challenges for RF modules in next-generation smartphones. In this paper, we propose a novel ultra-compact/low-loss SAW (UCLL-SAW) resonator structure featuring a reflector-less structure based on thin-film SAW (TF-SAW) technology. By forming end-faces for acoustic energy confinement and optimizing the interdigital transducer (IDT) design, we have realized a compact duplexer (DPX) with dimensions of 1.4 mm × 1.1 mm that achieves low insertion loss, high isolation, and excellent temperature stability. The proposed structure is applicable to both middle- and high-frequency bands. Furthermore, it suppresses reflector-induced spurious responses, thereby improving the performance of multiplexers for carrier aggregation. These advantages are expected to contribute to further innovation in RF systems.