Abstract: A high-isolation and anti-glue-invasion Surface Acoustic Wave (SAW) duplexer includes a transmitting filter and a receiving filter. The isolation of the duplexer is improved by adjusting the positions of parallel resonance arms of the receiving filter and optimizing the distances between a grounding metal wiring of a Double Mode Structure (DMS) filter in the receiving filter and other grounding metal wirings and a distance between the grounding metal wiring of the DMS filter in the receiving filter and a signal metal wiring, and the grounding metal wiring is further arranged to surround the series resonance arms and the parallel resonance arms, so as to fill blank positions between the resonance arms and the edge of a package.

Abstract: A duplexer is provided with high isolation and high steepness on low-frequency side of a receiving band, including an antenna terminal, a transmitting terminal and a receiving terminal arranged on a piezoelectric substrate, where a transmitting filter is connected between the antenna terminal and the transmitting terminal; a receiving filter, with a series arm and multiple parallel arms connected to the series arm, is connected between the antenna terminal and the receiving terminal; the series arm is provided with a DMS filter and multiple series arm resonators; each parallel arm is provided with a parallel arm resonator; and the DMS filter is in common ground connection with all the parallel arm resonators of the receiving filter. The duplexer can better improve the passband isolation and increase the steepness on the low-frequency side of the high passband without additional components and structural complexity, thereby improving performance and providing high practicability.