Abstract: A surface acoustic wave resonator arrangement comprises a piezoelectric substrate (100) and a surface acoustic wave resonator (110) which includes an interdigital transducer (111,112) disposed on the piezoelectric substrate (100). A trench (13 0) is disposed within the piezoelectric substrate (100) facing the resonator (110). Trench (130) causes reflected waves (143,144) in response to waves (141,142) leaking from the surface acoustic wave resonator. Trench (130) is configured such that the reflected acoustic waves (143,144) achieve phases at the edge (115) of the resonator (110) such that the accumulated phases of all the reflected waves received at edge (115) is zero or substantially zero, thereby avoiding constructive interference of the reflected waves with the acoustic waves resonating in the resonator. Thereby undesired acoustic coupling between resonators or influence of waves reflected at edges of the piezoelectric substrate or dicing lines is reduced.

Abstract: An antenna duplexer includes a transmission filter which operates in a transmission frequency band and has a transmission filter output. A reception filter operates in a reception frequency band and has a reception filter output. An antenna connection is connected to the transmission filter output and a matching element is connected between the antenna connection and the reception filter input. The circuit formed from the transmission filter, reception filter and matching element attenuates transmission signals in a frequency band whose frequencies f are in the interval 0.50*f0<=f<=0.75*f0, where f0 is the mid-frequency of the reception frequency band.

Abstract: An antenna duplexer includes a transmission filter which operates in a transmission frequency band and has a transmission filter output. A reception filter operates in a reception frequency band and has a reception filter output. An antenna connection is connected to the transmission filter output and a matching element is connected between the antenna connection and the reception filter input. The circuit formed from the transmission filter, reception filter and matching element attenuates transmission signals in a frequency band whose frequencies f are in the interval 0.50*f0<=f<=0.75*f0, where f0 is the mid-frequency of the reception frequency band.

Abstract: A duplexer includes an antenna terminal, a transmit filter, and a receive filter. The receive filter includes a first sub-filter that includes one or more resonators, and a second sub-filter including a double mode surface acoustic wave (DMS) filter. The second sub-filter is downstream of the first sub-filter relative to the antenna.