TX De-Emphasis

The PMA Direct interface has a bus, pma_tx_deemphasis[17:0], that provides the pre-emphasis, main cursor, and post-emphasis settings as follows:

  • Bits [17:12]—C+1 - post-emphasis setting
  • Bits [11:6]—C0 - main cursor setting
  • Bits [5:0]—C-1 - pre-emphasis setting

The following boundary conditions must be maintained:

  • C0+ | C+1 | + | C-1 | ≤ FS
  • C0- | C+1 | - | C-1 | ≥ 0.1875 * FS
  • C0 ≥ 0.5625 * FS
  • | C+1 | ≤ 0.375 * FS
  • | C-1 | ≤ 0.1875 * FS
Note: Refer to "pma_tx_deemphasis" in Table 5 for the pre-emphasis, main cursor, and post-emphasis setting.
The FS values are stored in the PHY_PMA_ISO_TX_FSLF[15:0] PMA register. The user application must read PMA register bit[13:8] to determine the C+1, C0, and C-1 values. The PHY_PMA_ISO_TX_FSLF address is:
  • Lane 0—24’h:20f008
  • Lane 1—24’h:20f108
  • Lane 2—24’h:20f208
  • Lane 3—24’h:20f308