10Base-T TD Circuit Common-Mode Output Voltage
1000BASE-T/100BASE-TX/10BASE-T Physical Layer Compliance Tests Manual
78
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continuous. It is import to ensure that the ground on test fixture 14-14is connect to a stable (not
floating) ground through the RJ-45 of the UUT.
Figure 20-1. Test Setup for 10BASE-T TD Circuit Common-Mode Output Voltage
2. From the 10 BASE-T PHY Configuration Tests menu in gigconf.exe, select the Common
Mode Output: 1411.10.09 test
3. Set scope settings for positive common-mode measurement as shown in table below.
Differential Probe
w/ 1 GHz BW
Unit Under Test
(UUT)
Digitizing
Oscilloscope
Test Fixture 14-14
100 Ohm Resistive Load
RX
RJ-45
TX
To Chassis
GND (can be metal shield on RJ-45)
Table 20-1. Scope Configuration for TD Circuit Positive Common-Mode Output Voltage
Scope Parameter
Setting
Horizontal Scale
25 ns/division
Vertical Scale
-80 mV to +80 mV (at 8 divisions, this equals 20 mV/
division)
Trigger Type
Positive edge
Trigger Level
Typically 0 V to +50 mV
Display Persistence
Infinite persistence