SNLS589B September 2016 – July 2018 DS90UB960-Q1
The AEQ circuit can be programmed with minimum and maximum settings used during the EQ adaption. Using the full AEQ range provides the most flexible solution, if the channel conditions are known however, an improved deserializer lock time can be achieved by narrowing the search window for allowable EQ gain settings. For example, in a system use case with a longer cable and multiple interconnects creating higher channel attenuation, the AEQ would not adapt to the minimum EQ gain settings. Likewise, in a system use case with short cable and low channel attenuation, the AEQ would not generally adapt to the highest EQ gain settings. The AEQ range is determined by the AEQ_MIN_MAX register 0xD5 (See Table 187) where AEQ_MAX sets the maximum value of EQ gain. The ADAPTIVE_EQ_FLOOR_VALUE determines the starting value for EQ gain adaption. To enable the minimum AEQ limit, the SET_AEQ_FLOOR bit in the AEQ_CTL2 register 0xD2 must also be set (See Table 184). An AEQ range (AEQ_MAX - AEQ_FLOOR) to allow a variation around the nominal setting of –2/+4 or ±3 around the nominal AEQ value specific to Rx port channel characteristics gives a good trade-off in lock time and adaptability. The setting for the AEQ after adaption can be read back from the AEQ_STATUS register 0xD3 (See Table 185). The suggested AEQ_FLOOR settings are given in Table 8.
|CHANNEL INSERTION LOSS AT 2.1 GHz (dB)||ADAPTIVE_EQ_FLOOR_VALUE|
|Up to –9.4||0|
|–9.4 to –13.2||2|
|–13.2 to –15.4||4|
|–15.4 to –17.8||5|
|–17.8 to –19.2||6|