2.8 Receive CTL Equalization

You can set the values to control the Continuous Time Linear (CTL) equalization of the receiver. The list contains four selections (Channel Characteristics) to control equalization for each of the enabled lanes (Figure 2-6).
  • User Defined
  • Short-Reach (Default)
  • Medium-Reach
  • Long-Reach
For the User Defined selection, you can enter values for Low Frequency Amplitude (dB), Cut-Off Frequency (MHz), and Impedance value (Ohms). For all other selections (Short-Reach, Medium-Reach, and Long-Reach), the values for Low Frequency Amplitude (dB), Cut-Off Frequency (MHz), and Impedance (Ohm) are set and read-only.

The Configurator sets the register values based on your selections (Short/Medium/Long Reach) and the Data Rate of the lanes as per the following table.

For example, if Short-Reach is selected, LANE<n>_RE_AMP_RATIO and LANE<n>_RE_CUT_RATIO lane registers are automatically set with values based on the Data rate of that Lane for Short-Reach.

Table 2-7. Amplitude/Cut-Off Frequency Ratio Register Values
FeatureControl RegistersConditionValue Programmed in Register
CTL EqualizationLANE<n>_RE_AMP_RATIO

LANE<n>_RE_CUT_RATIO

Data rate of 1G - 3G

Short‐Reach

LANE<n>_RE_AMP_RATIO = 0x0

LANE<n>_RE_CUT_RATIO = 0x0

Medium Reach

LANE<n>_RE_AMP_RATIO = 0x0

LANE<n>_RE_CUT_RATIO = 0x0

Long Reach

LANE<n>_RE_AMP_RATIO = 0x0

LANE<n>_RE_CUT_RATIO = 0x0

Data rate of 3G - 4GShort‐Reach

LANE<n>_RE_AMP_RATIO = 0x0

LANE<n>_RE_CUT_RATIO = 0x0

Medium Reach

LANE<n>_RE_AMP_RATIO = 0x0

LANE<n>_RE_CUT_RATIO = 0x0

Long Reach

LANE<n>_RE_AMP_RATIO = 0x20

LANE<n>_RE_CUT_RATIO = 0x0

Data rate of 4G - 5GShort‐Reach

LANE<n>_RE_AMP_RATIO = 0x0

LANE<n>_RE_CUT_RATIO = 0x0

Medium Reach

LANE<n>_RE_AMP_RATIO = 0x80

LANE<n>_RE_CUT_RATIO = 0x60

Long Reach

LANE<n>_RE_AMP_RATIO = 0x80

LANE<n>_RE_CUT_RATIO = 0x80

Note: LANE<n> denotes the lane number where <n> can be 0, 1, 2, or 3.