How to choose a real-time oscilloscope for jitter testing and analysis
With the significant increase in bus speeds in computer and communication systems, especially the increasing popularity of various high-speed serial buses using embedded clock technology, timing jitter has become a basic factor affecting their performance. This article focuses on how to choose a real-time oscilloscope for jitter testing and analysis based on the various current jitter testing tools and methods, and discusses several key factors in the oscilloscope that affect the jitter test results. Finally, reference methods and test examples are provided for high-precision jitter testing.
More and more high-speed computers and communication systems are beginning to use high-speed serial buses to transmit high-speed data between chips, backplanes and system devices. During the serial data transmission process, any tiny high-speed clock and data jitter will have a huge impact on the entire system. In this case, jitter has become the key to the success or failure of designing high-speed digital systems. The most typical application is that the traditional 33M PCI parallel bus is being replaced by PCI-Express using high-speed serial technology. The data rate supported by its latest standard has reached 5Gb/s, and the width of a UI is only 200ps. Any tiny jitter will Causing data transmission errors. Current timing margin specifications for various high-speed serial buses and data links indicate that tighter control of jitter throughout digital systems is a must. Only by comprehensively and effectively testing and analyzing jitter can its root causes be isolated, thereby reducing jitter and improving system performance and stability based on the causes of system jitter. PCI-Express, FBD, InfiniBand, SerialATA and DVI all have clear requirements for clock and data jitter. This article discusses the key factors that affect the jitter test results based on the real-time jitter test method performed by the oscilloscope.
Typical jitter test methods
In order to successfully design a high-speed digital system, it is not only necessary to understand what jitter is and calculate the size of the jitter, but also to isolate and decompose different jitter components and analyze the causes of jitter, so as to avoid system failures caused by jitter in high-speed systems. . Before understanding jitter testing, wisely choosing appropriate jitter testing tools and methods becomes the first step in the entire jitter testing work. There are currently several jitter test tools to choose from. The Bit Error Tester (BERT) directly tests the bit error rate of the system, but it is expensive and has a single function, which is not suitable for designers and debuggers. There are also functions of using a time interval analyzer to test jitter. Single, limited by insufficient jitter analysis capabilities. High-performance digital oscilloscopes have become the most popular jitter testing tools today.
