SAW filters and technology at CPqD-Telebras

The increasing interest in SAW devices is noted in different areas of communication. Fiberoptic (SONET and SDH), Personal Communications Systems (PCS), Cordless telephones, Advanced Mobile Phone System (AMPS), Global System for Mobile communication (GSM) and satellites communication systems are ranging from 70 MHz up to 2.5 GHz. For about two decades SAW filters are standard components in every TV IF stage. In radio link systems SAW channel, in IF satellite receivers and spectrum shaping filters are being preferred due to the excellent reproducibility of passband and stopband characteristics. A variety of new SAW structure were developed in order to achieve low insertion loss and high suppression of adjacent interferers. In the RF stage SAW devices compete with others filtering techniques, such as Micro Wave Ceramic (MWC). The use of standardized materials and process decreases fabrication cost and simultaneously increases product quality. Finally, the small size of SAW devices brought a breakthrough in circuit design leading to a growing use of SAW instead of MWC filters. This papers discusses the present and future SAW development at R and D Centre of Telebras