I've got a question to all you professional electronics engineers...
The analog PLL really is limited by the VCO.
Has anyone made a digital VCO?
Not a DCO, but a VCO that was programed by a DC voltage input accurate to the micro-volt.
Seems simple enough, but I have not done DCOs, DACs, FPGAs, Microprocessors, etc, etc...
If a digital VCO was made that could have a linear micro-voltage to frequency sweep of like, (1,000,000 : 1), the PLL would be propelled forward to having almost an instantaneous, unbreakable lock, with no jitter using active filters.
The only problem with active filters that I found was that even though they decrease the lock in time and create less jitter, the range of the PLL lock in is greatly decreased.
Just a thought...
BTW, I actually did alot of research on digital frequency multiplication, forgot what I was going to use it for...
If anyone is interested, make a thread and post what you got already, and maybe I can help.