17
PS8932C 07/31/08
PI3PCIE2612-B
High Bandwidth, 6-Differential Channel
1:2 DP/PCIe Gen2 Display Mux, BTX Pinout
0 1 2 3 4
-10
5 6 78
-45
-40
-35
-30
-25
-20
SDD21 Zref=85 Ohms
-15
Frequency, GHz
Differential Near End Crosstalk, dB
Figure 3: Illustration of different ial near end crosstalk requirement.
Switch Test Fixture Requirements
The test ¿ xture for switch S-parameter measurement shall be designed and built to speci¿ c requirements, as
described below, to ensure good measurement quality and consistency:
• The test ¿ xture shall be a FR4-based PCB of the microstrip structure; the dielectric thickness or stackup
shall be about 4 mils.
• The total thickness of the test ¿ xture PCB shall be 1.57 mm (0.62”).
• The measurement signals shall be launched into the switch from the top of the test ¿ xture, capturing the
through-hole stub effect.
• Traces between the DUT and measurement ports (SMA or microprobe) should be uncoupled from each
other, as much as possible. Therefore, the traces should be routed in such a way that traces will diverge
from each other exiting from the switch pin ¿ eld.
• The trace lengths between the DUT and measurement port shall be minimized. The maximum trace length
shall not exceed 1000 mils. The trace lengths between the DUT and measurement port shall be equal.
• All of the traces on the test board and add-in card must be held to a characteristic impedance of 50 Ohms
with a tolerance of +/- 7%.
• SMA connector is recommended for ease of use. The SMA launch structure shall be designed to minimize
the connection discontinuity from SMA to the trace. The impedance range of the SMA seen from a TDR
with a 60 ps rise time should be within 50+/-7 ohms.
08-0147
