This book is an excellent reference for anyone doing a PLL design. It covers topics relevant to current popular ICs and is especially attentive to the always troublesome issue of noise. Focus is primarily on tri-state charge pump phase detector PLLs which is appropriate since most modern PLLs are of this type.

I found the chapter about "fractional-N" PLLs particularly interesting.

"PLL Performance, Simulation, and Design" is an excellent modern suppement to other PLL books that I have by Rohde and Gardner.