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AR# 50146

7 Series FPGA GTH Transceivers - RX Termination Use Modes


This answer record describes the 7 series GTH Transceiver RX termination use modes for different protocols and usage scenarios.


The RX termination use modes are covered in this table. This is included in v1.8 of the 7 Series FPGAs GTX/GTH Transceivers User Guide (UG476) "RX Analog Front End" section.

Use Mode External AC Coupling Term Voltage Max Swing mVDPP Suggested Protocols and usage notes
1 On Gnd 1200 Port Settings:
RXDFEAGCTRL[4:3] = 2'b01
Attribute Settings:
RX_CM_SEL[1:0] = 2'b01
2 On AVTT 1200 Protocol:
Backplane in LPM Mode,
CEI-6 (1200 mVDPP) in LPM Mode,
Wireless in LPM Mode ,
Serial RapidIO in LPM Mode,
Port Settings:
RXDFEAGCTRL[4:3] = 2'b10
Attribute Settings:
RX_CM_SEL[1:0] = 2b00
3 On 800mV 2000 Protocols:
XAUI (1600 mVDPP),GbE,
PCI Express in DFE Mode and LPM mode
Backplane in DFE Mode,
CEI-6 (1200 mVDPP) in DFE Mode,
Wireless in DFE Mode,
Serial RapidIO in DFE Mode,
Interlaken in DFE and LPM Modes
Port Settings:
RXDFEAGCTRL[4:3] = 2'b10
Attribute Settings:
RX_CM_SEL [1:0] = 2b11
RX_CM_TRIM[3:0] = 4b1010
4 Off Float 2000 Protocol: GPON
Port Settings:
Depends on circuit implementation. Likely High Common Mode (Likely, RXDFEAGCTRL[4:3] = 2'b10)
Attribute Settings:
RX_CM_SEL[1:0] = 2b10

Note: This only works in LPM mode.
AR# 50146
Date Created 05/24/2012
Last Updated 07/05/2013
Status Active
Type General Article
  • Virtex-7
  • Virtex-7 HT