A full function Verilog(R) PLL logic model

Abstract

This paper describes the full function model of a phase-locked loop (PLL) in a logic simulator. In contrast to conventional models that bypass the PLL function, this Verilog model accurately represents all major characteristics of a PLL. It allows the simulation of the effect of the actual filter elements. It can accurately model clock deskew of a clock tree as well as synthesize other frequencies from the input clock. It produces a clock detect signal after a realistic lock sequence. The user has the option to add jitter to the PLL output. The model performs three orders of magnitude faster than an equivalent circuit model.