Agilent Technologies J-BERT N4903B Manual de usuario descargar pdf (Pagina 7)

User Interface and Measurement Suite

Quick eye diagram and masking

The quick eye diagram allows a one-shot check for a valid signal.

Due to the higher sampling depth of a BERT, the eye contour

lines visualize the measured eye at a deeper BER level for more

accurate results. Extrapolated eye contour lines display the eye

opening for even lower BER levels, such as 10

-15

, reducing the

measurement time significantly. The display shows numerical

results for 1- and 0- level, eye amplitude and width, total jitter

and more. Eye masks can be loaded from a library. Violations of

the captured eye mask are displayed. The result screen can be

printed and saved for documenting the test results (see Figure 6).

Figure 7. Spectral jitter decomposition for debugging jitter sources in a

design.

Figure 8. Eye contour with colors indicating BER level

Figure 6. Quick eye diagram with BER contour and masking

Figure 9. BERT scan including RJ/DJ separation, total jitter

Spectral jitter decomposition

The spectral jitter decomposition measures the spectral decom-

position of jitter components. When debugging designs, the jitter

decomposition simplifies identifying deterministic jitter sources

(see Figure 7).

Eye contour

The eye opening is a key characteristic of a device. The BER is

displayed as a function of sampling delay and sampling threshold.

Different views are available: eye contour (see Figure 8), pseudo

colors and equal BER plots.

BERT scan including RJ/DJ separation

This measurement shows the BER versus the sampling point

delay, which is displayed as a “bathtub” curve or as a histogram.

The measurement results are displayed in a table with setup and

hold time over phase margin, total jitter in rms or peak-to-peak,

and random and deterministic jitter. The measurement method is

equivalent to IEEE 802.3ae (see Figure 9).

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Agilent Technologies J-BERT N4903B Manual de usuario Pagina 7