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Moore’s Law claims that transistor density doubles every 18 months. Since transistor speed is roughly proportional to linear density, it implies that transistor speeds double every three years. R&D engineers need real-time oscilloscopes that can keep up with the “bandwidth curve” in order to bring new designs to market.
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Most users prefer a large oscilloscope display to a small display. Large displays are easier to view and provide more flexibility.
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This procedure describes the basic relations between the intrinsic skew jitter, observed jitter and the true jitter.
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There are two approaches to the present-day subject of jitter measurement, and the difference between them can lead to many misunderstandings when attempting to correlate results. There are the time interval analyzer (TIA) approach and the digital real-time oscilloscope (DRTO) approach.
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In the domain of jitter analysis for serial data streams and clocks, “transition density” is rarely an explicit subject, but assumptions concerning its’ value have (often unspoken) impact on conclusions concerning total jitter (Tj) and the assumed relations between Rj, Dj and Tj. The purpose of this discussion is to explain what “transition density” is and the role it plays in jitter analysis.
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The motivation for this White Paper is to understand the viability and justification of the methods prescribed by Wave-Crest™ with regard to obtaining periodic Jitter measurement results from pure time-time measurements.
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The determination of the total jitter is critical to the evaluation of current serial data standards whose high symbol rates leave small jitter margins. The accuracy of jitter measurements is challenged by these smaller margins. Most current jitter measurement techniques estimate the total jitter by breaking the measurement down into random and deterministic components and then add them together using a multiplier in front of the random component.
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In recent years, there has grown a variety of different ways to obtain estimations of what is called “Random Jitter” (Rj) and “Deterministic Jitter” (Dj). This discussion is about how to organize those methods into three basic categories, pertinent to three different sets of needs. Perhaps if nothing else, it will help the reader to keep the conflicting definitions and consequent differing measurement results from creating fear and doubt concerning jitter measurement.
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Jitter measurements are a critical element in the analysis and certification of serial data systems.With symbol rates above 2.5 Gb/s common in many current designs, the need to accurately characterize jitter is more important than ever. Central to all jitter measurements is a reference clock against which the symbol timing must be measured.
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The purpose of this document is to show that DDj or DCD+ISI measurements from a LeCroy SDA, a WAVECREST™ SIA3000, and a Sampling Oscilloscope are consistent within the pecifications of these instruments.The methods by which these three very different instruments perform this measurement is also discussed.
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