抖动和新的数字领域

Jitter and the New Digital Regime

更高速数字传输的发展不仅导致众多数字标准总线的出现,也使保证成功的设计需求发生了变化,即不仅要求功能正确,而且要求系统可靠。问题已从“它能工作吗?”变成“它能工作得多好?”。本文的主题就是通过对系统进行抖动测量和误码率(BER)测试在技术上回答上述问题。 应使用误码率确定数字系统鲁棒性的程度,误码率主要受所存在抖动程度的影响。本文对抖动作了介绍,讨论抖动来源,按产生的抖动特性对抖动源进行分类。有许多需要考虑的抖动因素,以及由此引发的各种增加或减少抖动的看法。文章介绍了这些看法及适用的相关标准,这些标准在哪些设计申能最为有效地使用。最后讨论今天的各种测试仪器工具,它们的能力和精度,以及在测量中的长处和不足。

Because of the relentless progression to higher speeds for digital transmission, there has not only been a proliferation of digital bus standards, but a shift in the design requirements in order to be successful. This shift has been one from considering only functionality to one of proving reliability. The question has gone from 'Does it work?' to 'How well does it work?' The way this question is answered technically through jitter measurements and bit error rate (BER) testing is the topic of this article. For digital systems the degree of robustness is determined by bit error rate which is heavily influenced by the degree of jitter present. Jitter is introduced and its sources are discussed and are categorized by characteristics of jitter they cause. There are many factors in the consideration of jitter and these lead to many viewpoints of jitter all of which yield insights into its source or mitigation. These viewpoints are introduced and related to standards when applicable, insights they can deliver and where in a design they are most effective. Finally, the test instrument tools available today that can deliver these views are discussed in terms of capabilities and accuracy along with their pros and cons in their measurement techniques.