1000Base-T Test Fixtures and Calibration Load Fixtures
1000BASE-T/100BASE-TX/10BASE-T Physical Layer Compliance Tests Manual
102
Intel Confidential
A.8
Fixture 40-28B
Fixture 40-28B is also used for the alien crosstalk noise rejection test.
A.9
Fixture 40-32
Fixture 40-32 is used to test common-mode output voltage and is required for IEEE 802.3, Section
40.8.3.3. A schematic for fixture 40-32 can be obtained in the IEEE 802.3 specifications.
A 47.5-ohm resistor is soldered to the end of each wire on each differential pair. At the opposite
ends, each pair of 47.5-ohm resistors is soldered together. Where the 47.5-ohm resistors are
soldered together, they are also both soldered to one of the square pins in the top row. All of the
47.5-ohm resistors, and all of the top-row square pins are insulated from the copper ground plane
by a layer of kapton tape. The bottom row of right-angle square pins are soldered to the copper
ground plane (diagram below shows the four solder joints in the bottom view just below “Output
V” on the label). The shield on the RJ-45 connector is soldered to the fixture’s copper ground
plane.
Note:
On the top-side, each top row square pin has a 49.9 ohm resistor soldered to it, which is not visible.
The other end of each 49.9-ohm resistor is soldered to the corresponding ground pin in the bottom
row of square pins.
Another way to visualize how the resistors are arranged:
On each test channel, two 47.5-ohm resistors and one 49.9-ohm resistor form a “Y.” A top-row
square pin is soldered to the center of the “Y.” The top-row square pin is soldered to all three
resistors, at this single point on the “Y.” The opposite end of the 49.9-ohm resistor is soldered
to a ground pin. Kapton tape insulates the top-row square pins and the 47.5-ohm resistors from
ground.
