A new SAW band reject filter and its applications in wireless systems

SAW notch or band reject filters can achieve very low insertion losses and withstand very high powers in their pass bands. Despite these very promising attributes relatively little work has been invested to develop this technology, and of the little work which has been conducted, most of it focused on developing narrow band notch filters to suppress single tone carriers. The present paper introduces band reject filters constructed of single pole resonators in the well known ladder topology. The ability to reject a specific band while providing significantly less than 1 dB of insertion loss in the pass band make this technology very attractive for the front end of base station receivers or handset transmit or receive chains. The paper discusses the design methodology, highlight the performance of several prototype filters and discuss the numerous applications which we are currently considering for these components. It is our belief that such components will find many applications in RF design and open new markets for SAW technology in wireless systems.