Synthesis and performance of medium bandwidth, low time-spurious, high out-of-band rejection SPUDT filters

This paper discusses the synthesis and performance of a family of medium (5 to 8%) fractional bandwidth SPUDT filters for a miniature UHF SAW channelizer. These filters employ chirped input and output transducers to overcome the otherwise limited electrode reflectivity needed for the required fractional bandwidth. They are designed to achieve moderate insertion loss, low time-domain spurious, and high out-of-band rejection without the need of electrical matching. A modified electrode-width controlled (EWC) scheme is devised to implement the desired transduction and reflection weightings