This application note discusses the effects of powersupply
noise interference on PLL-based clock
generators. It describes several measurement
techniques for evaluating the resulting DJ
(deterministic jitter). Relationships are derived
outlining how frequency-domain spur measurements
can be used to evaluate timing jitter behavior.
Laboratory bench-test results are used to compare
the approaches, and demonstrate how to reliably
assess the PSNR (power-supply noise rejection)
performance of a reference clock generator.
Index Terms
DJ (deterministic jitter); TIE (time interval error);
PLL (phase locked loop); PSNR (power-supply
noise rejection); PSI (power supply interference); SJ
(sinusoidal jitter)
1. Introduction
Low-jitter clock generation is the core timing
component in network equipment. As the serial link
rate continuously grows to meet the ever-increasing
bandwidth demand, timing jitter becomes a
significant percentage of the data bit period. The
overall jitter budget in a system can be classified
into two parts: random jitter and DJ. The random
jitter contribution of a clock generator is usually well
defined, and can be translated into a peak-to-peak
value for a given bit-error-rate threshold. However,
the DJ caused by the periodic PSI is often a major
concern for system design, due both to the existence
of the on-board switching supply and to the highspeed
digital switching circuits inside ASICs.
声明:本文内容及配图由入驻作者撰写或者入驻合作网站授权转载。文章观点仅代表作者本人,不代表电子发烧友网立场。文章及其配图仅供工程师学习之用,如有内容侵权或者其他违规问题,请联系本站处理。 举报投诉
全部0条评论
快来发表一下你的评论吧 !