Part Number: DS250DF410
Hello,
Could you please provide clarification on the following two points regarding the DS250DF410?
1. PRBS Polarity for CH2 When using the PRBS Generator/Checker functions, we observed that the polarity appears to be inverted for both the PRBS Generator output and the PRBS Checker reception on CH2. Due to the internal configuration of CH2, is it designed such that the polarity is inverted at both the input and output stages?
For your reference, we have already confirmed the following:
- No polarity inversion is present in the external circuitry or wiring.
- No polarity inversion is observed on CH0.
2. Continuous DFE Adaptation Could you please inform us of any potential disadvantages or precautions when enabling Continuous DFE Adaptation?
Furthermore, in Table 7-54 of the SNLU182H Programmer's Guide (Section 7.37 "Enable/Disable Continuous DFE Adaption"), the following settings are listed for enabling Continuous DFE Adaptation:
- DFE_CONT_ADPT_COUNT = 1
- CONT_ADAPT_VEO_CHNG_THRS = 15
- EN_DFE_CONT_ADAPT = 1
Regarding these settings, we would like to confirm the following details:
(1)
DFE_CONT_ADPT_COUNT = 1
The documentation describes this as a "look-beyond" counter. Could you please explain specifically what a setting of "1" means in the context of Continuous DFE Adaptation operation?
(2)
CONT_ADAPT_VEO_CHNG_THRS = 15
We understand that Continuous DFE Adaptation is triggered based on changes in VEO/HEO. Could you clarify what the setting value of "15" specifically corresponds to in terms of VEO change magnitude, and how the trigger threshold is determined?
(3)
CONT_ADAPT_HEO_CHNG_THRS
Although this parameter is not listed for modification in Table 7-54, could you please explain what the setting value corresponds to regarding HEO change magnitude, and its relationship with the trigger mechanism?
(4) Behavior of CTLE/DFE during Continuous Adaptation In our current evaluation, we are using Adapt Mode 2 (CTLE $\rightarrow$ DFE $\rightarrow$ CTLE) with Continuous DFE Adaptation enabled. During our tests, we observed that the CTLE boost values change simultaneously with the DFE tap changes when the received signal conditions shift.
Regarding this behavior, please clarify the following:
- When Continuous DFE Adaptation is triggered and DFE taps are readjusted, is it also possible for the CTLE to undergo readjustment/re-adaptation?
- Is there a possibility that receiving characteristics temporarily degrade—potentially causing bit errors or link status abnormalities—during the readjustment or switching of CTLE/DFE settings?
- Is there a specified guideline or maximum duration for the time it takes for CTLE/DFE values to stabilize after the adaptation process begins?
In our current evaluation, we have observed PRBS errors and link abnormalities detected by our test equipment near the timing when the CTLE/DFE values undergo significant changes.
Thank you in advance for your assistance.
Best regards,
K.Hirano