DS50PCI402_15 Datasheet, PDF (30/38 Pages) Texas Instruments – DS50PCI402 2.5 Gbps / 5.0 Gbps 4 Lane PCI Express Repeater with Equalization and De-Emphasis

DS50PCI402
SNLS320H – APRIL 2010 – REVISED MARCH 2013
www.ti.com
POWER SUPPLY BYPASSING
Two approaches are recommended to ensure that the DS50PCI402 is provided with an adequate power supply.
First, the supply (VDD) and ground (GND) pins should be connected to power planes routed on adjacent layers
of the printed circuit board. The layer thickness of the dielectric should be minimized so that the V_DD and GND
planes create a low inductance supply with distributed capacitance. Second, careful attention to supply
bypassing through the proper use of bypass capacitors is required. A 0.01 μF bypass capacitor should be
connected to each V_DD pin such that the capacitor is placed as close as possible to the DS50PCI402. Smaller
body size capacitors can help facilitate proper component placement. Additionally, three capacitors with
capacitance in the range of 2.2 μF to 10 μF should be incorporated in the power supply bypassing design as
well. These capacitors can be either tantalum or an ultra-low ESR ceramic.
Typical Performance Eye Diagrams and Curves
DS50PCI402 Return Loss
0
-5
-RL_RX-CM (S11)
-10
-RL_RX-DIFF (SDD11)
-15
S11
-20
SDD11
-25
-30
-35
-40
0.00
0.50
1.00
1.50
2.00
2.50
Frequency (GHz)
Figure 9. Receiver Return Loss Mask for 5.0 Gbps
0
-5
-RL_TX-CM (S11)
-10
-RL_TX-DIFF (SDD11)
-15
S11
-20
-25
SDD11
-30
-35
-40
0.00
0.50
1.00
1.50
2.00
2.50
Frequency (GHz)
Figure 10. Transmitter Return Loss Mask for 5.0 Gbps
30
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