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Ixiasoft
3.1.1.1.2. TX Equalizer
The FFE or TX equalization filter has one post-cursor tap, three pre-cursor taps and one main tap (attenuation). The frequency response of the filter is chosen to compensate for the channel impairments such as intersymbol interference (ISI), crosstalk, frequency-dependent losses and reflections. When a signal is transmitted over a channel, the high-frequency components get attenuated. To save power, de-emphasis is used instead of pre-emphasis. This results in a bit stream which is pre-distorted by the equalizer over several bits.
Parameter | Mode |
---|---|
Attenuation (ATTN) | PAM4, NRZ |
Post-tap1 (POST) | PAM4, NRZ |
Pre-tap1 (PRE1) | PAM4, NRZ |
Pre-tap2 (PRE2) | PAM4, NRZ |
Pre-tap3 (PRE3) | PAM4, NRZ |
Refer to the resources linked below to help calculate transmitter equalization.
Details on TX equalization settings for PAM4 and NRZ signals
TX equalization parameters take the following range.
Cursor | Rule | Step Size |
---|---|---|
ATTN | 0 ≤ ATTN ≤ 26 | 18.5 mV/step (0.17 dB) |
POST | -18 ≤ POST ≤ 18 Increment/decrement by 2 |
18.5 mV/step (0.34 dB) |
PRE1 | -10 ≤ PRE1 ≤ 10 Increment/decrement by 2 |
18.5 mV/step (0.34 dB) |
PRE2 | -15 ≤ PRE2 ≤ 15 | 9.25 mV/step (0.17 dB) |
PRE3 | -1 ≤ PRE3 ≤ 1 | 9.25 mV/step (0.17 dB) |
For more details on TX equalization programmability, refer to the description for code 0x0015 in the PMA Attribute Codes section.
The ATTN/PRE/POST taps can be dynamically changed via the Avalon® memory-mapped interface.
For more details on PMA attribute support and programming, refer to PMA/PCS Avalon® Memory-Mapped Interface Register Map and PMA Attribute Codes to configure these parameters.