EZJIT Jitter Analysis Software for Infiniium Series Oscilloscopes

Features of the EZJIT Software that Optimize Jitter Analysis Include:

• Easy-to-use jitter wizard
• Access up to 16 real-time measurement trends and histograms
• Fully functional with other Infiniium software such as Equalization and InfiniiSim
• Jitter spectrum display

With the faster edge speeds and shrinking data valid windows in today’s high-speed digital designs, insight into the causes of signal jitter is critical for ensuring the reliability of your design. EZJIT jitter analysis software from Keysight Technologies, Inc. combined with Infiniium Series oscilloscopes. provide insight necessary to evaluate signals and improve your designs. Jitter histograms, trends, and spectra time correlated to the real-time signal make it easy to trace jitter sources. Deep memory, extensive parametric analysis and advanced clock recovery ensure you can make the required measurements on the desired signals, with confidence.

Jitter Analysis Made Easy

A wizard in the EZJIT jitter analysis software helps you quickly set up the Infiniium oscilloscopes and begin taking measurements. With time-correlated jitter trend and signal waveform displays, the relationships between jitter and signal conditions are more clearly visible. Intuitive displays and clear labeling of information make it easy to comprehend measurement results.

Real-Time Trend, Histogram, and Spectrum Displays

Measurement data can be viewed as a trend display (Figure 6), showing a time plot of the measurement time-correlated with the signal waveform data. This makes it easy to understand relationships between jitter and signal conditions, such as intersymbol interference (ISI).

The histogram display (Figure 7) plots the relative occurrence of values for the measured parameter. The histogram provides insight into the statistical nature of the jitter. For example, the histogram shown in Figure 7 appears as two gaussian distributions. The peak-to-peak jitter between the gaussians indicates significant deterministic jitter in the signal, while the gaussians show the spread of random jitter.

The spectrum display (Figure 8) shows the spectral content of the jitter. The spectrum display can be useful for identifying sources of jitter by their frequency components. For example, if you suspect a switching power supply with a switching frequency of 33‑KHz is injecting jitter, you can test your theory by examining the jitter spectrum for a peak at 33‑KHz.

Flexible Clock Recovery

You can choose constant-frequency or phase-locked loop (PLL) clock recovery as well as use an explicit clock on another input channel to time the data transition. With PLL clock recovery, the data rate and loop bandwidth are adjustable.

Many standards allow the use of spread-spectrum clocking to avoid concentrating EMI and RFI at specific frequencies. Spread-spectrum clocking is simply FM modulation of the clock frequency, usually at some frequency well below the clock frequency. The bandwidth of the PLL in the receiver hardware allows it to track the slow change in the clock frequency while allowing faster changes to be measured.

Deep Memory Captures Low-Frequency Jitter

Deep memory is especially valuable for jitter analysis. The optional 2 Gpts memory on the Keysight 90000 X-Series and Z-Series is helpful in measuring low frequency jitter. At a sample rate of 80 GSa/s and incoming data rate of 2.5 Gb/s, 2 Gpts allows you to capture jitter frequency components down to 40Hz. Comparably in the 90000A, 9000 and S-Series, the 20 GSa/s sample rate and optional 1 Gpts memory allows you to capture jitter frequency components as low as 40 Hz. In some cases, measuring low- frequency jitter is not required; for example, the clock recovery PLL in most serial data receivers can reject jitter very effectively at moderately low frequencies. But sometimes an event occurring at a low repetition rate can cause bursts of jitter or noise with higher frequencies that the PLLcannot reject.

An example is shown in Figure 11. The upper yellow trace is a serial data signal. The middle green trace shows an uncorrelated aggressor signal that is causing short-term bursts of jitter in the data signal. The lower purple trace, showing a jitter trend signal derived from the serial data signal, plots the timing of each edge in the data stream compared to the “ideal” recovered clock. You can see a burst of timing errors that coincides with each transition in the middle green signal.