A 622.08 MHz narrow bandwidth SAW filter for clock recovery

This paper describes the development of a 622.08 MHz surface acoustic wave (SAW) filter for use in clock recovery units to recover the clock signal from NRZ (non-return-to-zero) data streams in SONET and SDH systems. A narrow bandwidth filter (less than 0.2%) using two different interdigital transducers (IDTs), working on two different harmonic frequencies, was designed and fabricated by the R&D Centre of Telebras. A description of the design and the fabrication are summarized and measurement results of the SAW filter are shown.