Electronic SystemS TF-108 Manuel de l'opérateur télécharger pdf (Page 23)

TF-DSQ Probe Calibration and Deskew Fixture

TF-DSQ-OM-E RevC

Now, let's assume that these probes are applied to signals with the same risetime, but a

different risetime than the one applied by the deskew fixture:

This example clearly illustrates how the application of signals with the same risetime (but

different risetime than the one applied by the deskew fixture) produces a deskew error, unless

compensated. In the previous figure, the green trace is the actual signal applied to the probes

that has a risetime of twice that employed by the fixture. The red and blue traces represent the

trace acquired through the probes and channel due to this edge. Because of the different

risetime applied, there is a small error.

A possible solution to this would be to vary the risetime of the edge applied to the probe by the

fixture; a very difficult design. Despite this difficulty, a variable risetime solution would require

knowing what the measured risetimes would be ahead of time or to measure the risetimes first.

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Electronic SystemS TF-108 Manuel de l'opérateur Page 23