Keysight Technologies E5400-Pro Series, User Manual

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60 Keysight Technologies E5400-Pro Series Soft Touch Connectorless Probes User’s Guide
4 Operating the E5402A, E5405B, and E5406A-Pro Series Probes
Eye Opening
The eye opening at the logic analyzer is the truest measure of an analyzer's
ability to accurately capture data. Seeing the eye opening at the logic
analyzer is possible with Eye Scan. The eye opening viewed with Eye Scan
helps the user know how much margin the logic analyzer has, where to
sample and at what threshold. Any probe response that exhibits overshoot,
ringing, probe non-flatness, noise, and other issues all deteriorate the eye
opening seen by the logic analyzer. The following eye diagrams were
measured using E5402A, E5405B, and E5406A-pro series soft touch
probes and Eye Scan while probed mid-bus on a 50
Ω
transmission line
load terminated at the receiver. The data patterns were generated using a
2
23
-1 pseudo random bit sequence (PRBS).
Figure 40 Eye opening measurement schematic (E5402/05/06A)
The following plots were made on a Keysight 16760A logic analyzer using
a Keysight 8133A pulse generator with a 250 ps rise time converter. The
following measurements use Eye Scan to show the margin at 800, 1250,
and 1500MT/s. The amplitudes are indicated in the captions.
E5382A
Probe
Z0=50 Ω
Rterm
Driver Receiver
Rsource
PRBS
output
50 Ω
Z0=50 Ω
50
Ω
Logic
Analyzer
w/ EyeScan