Mmm, I am a bit clearer now.
Another question, the PLL can be designed to be a first-order PLL or second-order PLL. How do you design such PLL systems such that they have different order transfer function characteristics? I have just learn feedback theory, systems and control course, and I still do not know how to find the transfer function of a system H(s) with a feedback transfer function H1(s).
And what is the meaning of steady state phase error?
My conception of steady-state phase error is the steady state phase error output signal when passed through the PLL system, and since the PLL is designed to be stable (in phase lock), the steady state phase error will be finite, and we can use the final value theorem of Lasplace tranform to work out its steady state phase error value.
Hope I am correct.