If 1ns/bit resolution of phase comparator was achieved in classical method, it require a counter with 1GHz sampling clock.
So, with classical phase detector, such as JK flipflop, we can get a phase error pulse. Then, After proportionally expanding the width of the pulse with a integral cuicuit, the high resultion phase detector by low frequency clock may be implemented.
I am seeking a appropriate pulse expanding cuicuit now. Could you give me some suggestions? Thanks!