1000BASE-T/100BASE-TX/10BASE-T Physical Layer Compliance Tests Manual
Intel Confidential 35
100BASE-TX Waveform Overshoot
9 100BASE-TX Waveform Overshoot
ANSI Section 9.1.3
9.1 Test Purpose
To measure the overshoot of the differential waveform.
9.2 Specification
“For the purposes of 9.1, overshoot is defined as the percentage excursion of the differential signal
transition beyond its final adjusted value, V
OUT
, during the symbol interval following the signal
transition. The adjusted value is obtained by performing a straight line best fit to an output
waveform consisting of 14 bit times of no transition preceded by a transition from zero to either
plus or minus V
OUT
as shown in [Figure 9-1].
V
OUT
is defined to be the intersection of the straight line best fit for amplitude with the vertical line
indicating the start of the transition from 0 V to V
OUT
.
The differential signal overshoot shall not exceed 5%. Any overshoot or undershoot transient shall
have decayed to within 1% of the steady state voltage within [8.0] ns following the beginning of the
differential signal transition.”
1
Figure 9-1. Waveform Overshoot at Active Output Interface
2
1. ANSI X3.263-1995, p 29.
2. Based on ANSI X3.263-1995, p 29, figure 12.
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