Honored ContributorHello, I am designing a board with differential LVDS interfaces (receive).
I want to use the internal differential termination Rd and the manual is not very explicit on whether the RZQ resistor has to be present or not. Does anyoen has a definite answer ? Thanks Pascal
Honored ContributorI don't agree. The device manual is quite clear about the fact that Rd on-chip-termination for LVDS inputs doesn't use calibration - and thus doesn't depend on RZQ.
Honored ContributorHonored ContributorYou may want a clearer explanation in the manual, but it does distinguish between "OCT with calibration" and just "OCT" (without calibration). There's a table summarizing all available OCT variants, it says which of it have calibration.
Technically, OCT calibration is provided for those termination schemes that are using transistors as load, basically the same feature that provides programmable current strength. Differential Rd uses fixed termination, GX transceivers have calibrated differntial OCT.Honored ContributorHonored ContributorThis doesn't make any sense : Cyclone 5 does not have OCT Calibration for LVDS interface. Based on Cyclone 5, you have %40/50 variations based on PVT. How come there is no calibration. Is there any Altera AE looking for this thread?
Honored ContributorRZQ is used for External memory interface IP ,such as DDR3. LVDS can use only internal register,which can set in assignment editor.
