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27 February 2015

Using Histograms (Part II)

Figure 1: A flip-flop's propagation delay is a typical spec that can be derived using statistical analysis
Figure 1: A flip-flop's propagation delay is a typical spec
that can be derived using statistical analysis
In Part I of this series, we looked at some of the basics of histograms and how they can provide a statistical view into random variation of signal parameters. Next, let's look at how histograms can help us use statistical analysis to determine product specifications.

09 February 2015

Using Histograms (Part I)

Histograms of the period, width, and TIE of a clock waveform show different distributions of  time jitter
Figure 1: Histograms of the period, width,
and TIE of a clock waveform show
different distributions of time jitter
When we measure parameters of a waveform in a circuit or device, we rarely take a single measurement but rather a significant number of measurements. We want to see trends over time in the period, width, and time-interval error of a clock pulse, for example. Those parameters will have some nominal value, but there will typically be some random variation that we refer to as jitter.