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New ContributorIO Standard for GTS Transceiver REFCLK
Hi, We use on the Agilex 5 and 3 Transceivers with AC coupling.
Agilex 5 requires CML, HCSL in Agilex 5 datasheet.
However, Agilex 5 Premium kit uses LVDS Clock for some Transceiver REFCLK.
Is it possible to use LVDS as REFCLK for XCVRs when we use with AC Coupling ?
Yes — LVDS can be used as a REFCLK for Agilex 5 (and Agilex 3) transceivers if it is AC‑coupled and its common‑mode voltage/swing are translated into the allowed CML/HCSL input range.
2 Replies
erencuhadarNew Member
Hello JonWay_altera,
Datasheet states that REFCLK should be HCLS or CML. You stated LVDS can also be used as REFCLK if it is AC-coupled but in AGILEX 5 FPGA E-SERIES 013B DEVELOPMENT BOARD (the reference design), it is used without AC- coupling:
Besides, I am confused about that, how the voltage swings of LVDS and CML/HCSL be same and why the datasheet does not mention LVDS?
JonWay_alteraFrequent Contributor
Yes — LVDS can be used as a REFCLK for Agilex 5 (and Agilex 3) transceivers if it is AC‑coupled and its common‑mode voltage/swing are translated into the allowed CML/HCSL input range.
