Best Probing Practices
Because of the variables L, di, and dt, you may be unsure how much margin
is available in your measurement setup. The following are guidelines for good
probing practices:
•
The ground lead from each channel group (0-7 and 8-15) should be
attached to the ground of the circuit under test if any channel within the
group is being used for data capture.
•
When capturing data in a noisy environment, every third probe’s ground
should be used in addition to the channel group’s ground.
•
High-speed timing measurements (T
R
< 3 ns) should make use of each
probe’s own ground.
When designing a high-speed digital system, you should consider designing
dedicated test ports that interface directly to the instrument’s probe system.
This will ease measurement setup and ensure a repeatable method for
obtaining test data.
Ensuring Accurate Measurements
Probing the Circuit Under Test
142
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