DS110DF410 - ADR 0x70[2:0] CTLE Adaptation Look-Beyond Count

Kawai-San,

I am re-wording the DS125DF410 description with more details of this feature. Hopefully this would describe a more precise picture of the actual device operation and a better understanding of the register 0x70[2:0] operation.

When the device is attempting to lock to an incoming signal, signal is lost and then recovered, or the HEO or VEO threshold is reached, the CTLE adaptation algorithm sets the CTLE boost to a predetermined boost setting. Each boost settings provides more high frequency boost. Please note table 14 of the DS125DF410 data sheet. The device starts with the boost settings from register(Hex) 0x40, then 0x41, …, until it gets to the boost settings specified in register 0x5F. The DS125DF410 attempts to phase lock to the equalized signal after each boost setting. If the phase lock succeeds, the device measures the Horizontal and Vertical Eye Openings(HEO and VEO) using the internal eye monitor circuit. Using the HEO and VEO, the device computes a figure of merit to compare HEO and VEO readings with the previous boost settings. While the figure of merit continues to improve, the device continues to try additional boost settings from the table until the figure of merits stops to improve and begins to degrade. When the figure of merit starts to degrade, the device still continues to try additional settings in the table. The number of additional settings is specified by register 0x70[2-0]. In default mode, this register is set to 3. This means the device attempts three additional boost settings. For example, if the last improvement was at the boost settings at register 0x50, the device tries boost settings at locations 0x51, 0x52, and 0x52(i.e three additional settings). If no improvements in the figure of merit results or it degrades, then it resets the CTLE boost values to those that produced the best figure of merit(i.e the best HEO and VEO).

Regards,,,nasser