Hi,
I'm trying to find the jitter produced by my DLL. To do this, I ran a transient simulation until the DLL locked. I then measured the voltage on the charge pump and inserted an ideal voltage source with the charge pump's final voltage value in parallel with that charge pump, allowing me to now run the DLL open-loop. I then ran pss and pnoise to measure the jitter at the output of the DLL.

The input reference frequency is 2GHz. pnoise gave me that Jee was in the ~100fs range, but Jcc was ~20ns, and Jc was ~1us! This is kind of strange, as the input reference period is only 500ps, and there should be no long term jitter in a DLL. I also ran the transient noise simulation, which gave me roughly the same amount of jitter as Jee.

Could anyone please provide some insight as to why these numbers are so different?

Thanks!