High-Speed Serial I/O Termination; Figure D-3: Transmit Termination; Figure D-4: Receive Termination - Xilinx RocketIO X User Manual

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High-Speed Serial I/O Termination

Virtex-II Pro on-chip termination is programmable to 50Ω or 75Ω . Virtex-II Pro X
transceivers support only a fixed 50Ω on-chip termination.
The output driver and termination are powered by VTTX at 1.5V. This configuration uses
a CML approach with 50Ω to TXP and TXN as shown in
The receiver termination supply (VTRX) is the center tap of differential termination to RXP
and RXN as shown in
high-side, low-side, and differential (floating or active). This configuration supports
receiver termination compatible to Virtex-II Pro devices, using a CML (high-side)
termination to an active supply of 1.8-2.5V. For DC coupling of two Virtex-II Pro X devices,
a 1.5V CML termination for VTRX is recommended.
172
Appendix D: Virtex-II Pro to Virtex-II Pro X FPGA Design Migration
50Ω

Figure D-3: Transmit Termination

Figure D-4. This supports multiple termination styles, including
VTRX
50Ω
RXP
RXN

Figure D-4: Receive Termination

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Figure D-3.
VTTX (1.5V)
50Ω
TXP
TXN
x700_03_022103
50Ω
x700_04_022103
RocketIO™ X Transceiver User Guide
UG035 (v1.5) November 22, 2004