XP IOB Pre-emphasis and Equalization

Versal Adaptive SoC SelectIO Resources Architecture Manual (AM010)
Document ID
AM010
Release Date
2024-03-18
Revision
1.5 English

Equalization

For challenging, high-speed links, the XP IOB receiver provides several different levels of equalization designed to increase the eye opening for LVDS15, DIFF_LVSTL_11, DIFF_LVSTL06_12, DIFF_POD12, LVSTL_11, LVSTL06_12, and POD12 interfaces. For LVDS15 interfaces, AC coupling is recommended when equalization is used. The EQUALIZATION attribute uses the following syntax in the XDC file:

set_property EQUALIZATION VALUE [get_ports port_name]
Table 1. Typical Gain for Different Values of Equalization
Value Estimated Gain (dB)
LVDS15 MIPI_DPHY DDR4 LPDDR4
EQ_NONE No gain. For use on DC coupled links.
EQ_LEVEL0 No gain. For use on AC coupled links.
EQ_LEVEL1 0.59 0.02 1.42 0.59
EQ_LEVEL2 1.09 0.43 1.91 1.09
EQ_LEVEL3 1.69 0.94 2.49 1.69
EQ_LEVEL4 2.14 1.36 2.94 2.14
EQ_LEVEL5 N/A 1.86 N/A N/A
EQ_LEVEL6 N/A 2.26 N/A N/A
EQ_LEVEL7 N/A 2.46 N/A N/A
EQ_LEVEL8 N/A 2.66 N/A N/A

Transmitter Pre-emphasis

For high-speed interfaces on lossy channels the XP IOB driver provides the ability to enable several levels of pre-emphasis for LVDS_15, LVSTL_11, and POD drivers. Transmit pre-emphasis is only supported when using the XPHY in the XP IOB.

The LVDS_PRE_EMPHASIS attribute uses the following syntax in the XDC file when the LVDS15 standard is used:

set_property LVDS_PRE_EMPHASIS TRUE/FALSE [get_ports port_name]
The PRE_EMPHASIS attribute is used for LVSTL_11, and POD drivers as well as their differential equivalents and is only compatible with a FAST slew rate and an OUPTUT_IMPEDANCE value of 40Ω (RDRV_40_40). The PRE_EMPHASIS attribute uses the following XDC command:
set_property PRE_EMPHASIS RDRV_240 [get_ports port_name]
Table 2. Typical Pre-emphasis Value
Attribute Value Estimated Gain (dB)
LVDS_PRE_EMPHASIS or PRE_EMPHASIS TRUE (LVDS_PRE_EMPHASIS) or RDRV_240 (PRE_EMPHASIS) 2.5