Communications: Timing Chips Take On Tight Margins In Sonet SDH And PDH Systems

Sonet/SDH and plesiochronous digital hierarchy (PDH) systems can take advantage of a timing-chip duo to achieve exceptional performance. The ZL30106 digital phase-locked loop (PLL) offers an OC-3 jitter compliance margin of 20 ps rms and features hitless reference switching, reference monitoring, and holdover. It accepts three input references, provides a range of output clocks, and achieves a holdover frequency accuracy of 0.01 ppm. The ZL30416 analog PLL performs jitter attenuation and rate conversion for Sonet/SDH equipment. It meets the requirements of line-card applications from OC-3/STM-1 up to OC-192/STM-64 transmission rates. Ultra-low-jitter output clocks meet Telcordia GR-253-CORE jitter specifications up to OC-192. Available in a 64-lead TQFP, the ZL30106 sells for $15 each in 1000-unit lots. The ZL30416 APLL, housed in a 64-contact CBGA, is priced at $36.19 each in 1000-unit quantities.