Kyocera’s SD25 is a small, lightweight Surface Acoustic Wave (SAW) Duplexer with a built-in matching circuit featuring improved attenuation and isolation characteristics. Duplexer is a component that is used in an antenna circuit, to enable duplex and simultaneous conversation by discriminating transmitting and receiving signals. It is mainly used in the circuits of a CDMA system, where it is a critical component that determines telephone speech quality.
Kyocera developed the Duplexer SD25 series of Chip Size Package (CSP) by taking advantage of its unique simulation technology that mounts minimized SAW element directly on ceramic substrate, seals it and coats it with resin. Optimizing the combination of the SAW element and the substrate enables the Duplexer to be as small as 2.5 x 2.0 x 0.8 mm (typical value), making it one of the smallest duplexers in the industry. The product offers excellent resistance to climate and mechanical impact thanks to its airtight structure, which seals with soldering the surrounding of the element mounted on the substrate.
Low Temperature Co-fired Ceramics (LTCC) is used as ceramic substrate. It allows an inductor for a matching circuit to be incorporated. As a result, the SD25 series requires no external inductor that is normally used for a matching circuit. This helps simplify circuit design while reducing the number of components and saving the component assembly space.
The products have two different specifications, one for Japanese CDMA (Japan CDMA Band) and the other for North American CDMA (Cellular Band). Kyocera plans to develop products for the UMTS bands in the near future. The SD25 series is also an environmentally friendly product using lead-free materials, and complies with the RoHS Directive.