Programmable Devices
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Altera PLL and serializer with phase shift


Hello! I am looking for help with a SERDES setup using Quartus. First a brief problem description and then I will provide more details below.


The 10-to-1 serializer is driven with two external clocks. I am feeding the input on the rising edge of the slow clock and 400ns later (in ModelSim at least) I get the serialized output out of Altera's Soft LVDS block. Each individual output state is aligned with the fast clock, but I do not see any output clock that I can use to tell the receiver when a new block of data begins. Where do I get a slow clock signal that's aligned with the SERDES output start?



Boring details:

I am new to FPGAs and after completing a number of tutorials I found this nice HDMI one here:

As far as I can tell the signal generation for the three 10-bit channels is working fine, the last piece is getting those channels serialized and sent via the dedicated LVDS pins of the Altera MAX 10 that I am using.

I am using an ALTPLL block to create the basic signal clock C0 and a secondary C1 clock which is 5 times faster (according to Soft LVDS documentation). Each channel goes into an Altera LVDS instance (configured for external PLL) along with the two clock signals. Running the whole thing in ModelSim I see the expected data going in an coming out. The problem is, where can I grab a clock that is synchronized to the LVDS output? Can I rely on the simulation and add a 400ns delay or add another slow clock output with a 144 degree phase shift? Those ideas don't sound too great, so what is the recommended solution?

(Note: this is not the final clock speed, I am trying to slow things way below HDMI specs just so I can confirm waveforms on my slow oscilloscope)

Quartus project folder:


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Hello Marco , Can you tell me what is setting you used in the ALTPLL ? Especially what is the compensation mode selected ? Thank you, Regards, Sree