Unlocking the Phase Lock Loop - Part 1
A Great Tutorial on the Operation of the Phase Locked Loop. Part 1 of this tutorial starts out with the basics. Includes details on the PLLs operation illustrated by derivations, Figures and Examples.

from www.complextoreal.com - An Intuitive guide to Principles of Communication

Unlocking the Phase Lock Loop - Part 2
A Great Tutorial on the Operation of the Phase Locked Loop. Part 2 of this tutorial  covers more concepts related to the PLLs operation including Tracking and acquisition of the signal, Effects of Noise and more…

from www.complextoreal.com - An Intuitive guide to Principles of Communication

Phase Locked Loop Design Fundamentals
The fundamental design concepts for phase-locked loops implemented with integrated circuits are outlined. The necessary equations required to evaluate the basic loop performance are given in conjunction with a brief design example. 

An Application Note from Motorola

Phase Locked Loop Fundamentals
An Application Note that goes over the fundamentals of a phase Lock Loop with details on its Structure and operation.  

from Mini Circuits

What Exactly is a PLL
This Article goes over the History of the Phase Lock Loop (PLL), its structure, some circuit examples and Applications.

by Tony van Roon - The History and Basic Explanation of the PLL