1000BASE-T/100BASE-TX/10BASE-T Physical Layer Compliance Tests Manual
Intel Confidential
53
100Base-TX Duty Cycle Distortion (DCD)
4. Measure the relative peak voltage of the waveform.
5. Calculate the 50% values. See
Figure 13-3. 16 ns Pulse Peaks Used to Calculate 50% Levels
6. Zoom in on the waveform to get the best resolution.
7. Select the split-dot (paired) cursors. Move on cursor to +V
OUT
/2 on the rising edge of the
waveform and move the other cursor to +V
OUT
/2 on the falling edge of the waveform. See
8. Confirm that the deviations of the 50% crossing times do not exceed ±0.25 ns.
In other words, the pulse should conform to the following: 15.50 ns
≤
Pulse Width
≤
16.50 ns.
9. Record the results.
10. Repeat steps 4 through 9 for the mid-level negative waveform, as shown in
11. Verify the measurements meet specifications.
Pulse Width Triggering
Triggering information is provided to give a good starting point for measurement. The
following guidelines will help the tester achieve the most stable display.
1. Set the trigger level to approximately 400 mV.
2. Select pulse width triggering.
3. Set the upper bound parameter to approximately 30 ns and the lower bound
parameter to approximately 2 ns.
4. Set the trigger mode to normal.
5. Increase the lower bound parameter gradually until the triggering is lost.
6. Decrease the lower bound parameter slowly in 5 ns increments until triggering
resumes.
7. Decrease the upper bound parameter until it is 5 ns to 15 ns above the lower trigger
bound parameter.