ZHCSKE8D March 2016 – October 2019 DS250DF410
PRODUCTION DATA.
A 5-tap DFE can be enabled within the data path of each channel to assist with reducing the effects of crosstalk, reflections, or post cursor inter-symbol interference (ISI). The DFE must be manually enabled, regardless of the selected adapt mode. Once the DFE has been enabled it can be configured to adapt only during lock acquisition or to adapt continuously. The DFE can also be manually configured to specified tap polarities and tap weights. However, when the DFE is configured manually the DFE auto-adaption should be disabled. For many applications with lower insertion loss (i.e. < 30 dB) lower crosstalk, and/or lower reflections, part or all of the DFE can be disabled to reduce power consumption. The DFE can either be fully enabled (taps 1-5), partially enabled (taps 1-2 only), or fully disabled (no taps).
The DFE taps are all feedback taps with 1UI spacing. Each tap has a specified boost weight range and polarity bit.
| DFE PARAMETER | DECIMAL (REGISTER VALUE) | VALUE (mV) (TYP) |
|---|---|---|
| Tap 1 Weight Range | 0 - 31 | 0 – 217 |
| Tap 2-5 Weight Range | 0 - 15 | 0 – 105 |
| Tap Weight Step Size | NA | 7 |
| Polarity | 0: (+) positive; feedback value creates a low-pass filter response, thus providing attenuation to correct for negative-sign post-cursor ISI | |
| 1: (-) negative; Feedback value creates a high-pass filter response, thus providing boost to correct for positive-sign post-cursor ISI. | ||