Limitations of PLL simulation: hidden oscillations in MatLab and SPICE

TL;DR

This paper discusses the limitations of numerical simulations in analyzing PLL circuits, highlighting how hidden oscillations can be missed in MatLab and SPICE, potentially leading to incorrect conclusions about circuit operability.

Contribution

It reveals the shortcomings of common simulation tools in detecting hidden oscillations in PLL circuits, emphasizing the need for careful nonlinear analysis.

Findings

Hidden oscillations may be missed in standard simulations.

Examples demonstrate potential for incorrect conclusions.

Simulation tools have limitations in nonlinear PLL analysis.

Abstract

Nonlinear analysis of the phase-locked loop (PLL) based circuits is a challenging task, thus in modern engineering literature simplified mathematical models and simulation are widely used for their study. In this work the limitations of numerical approach is discussed and it is shown that, e.g. hidden oscillations may not be found by simulation. Corresponding examples in SPICE and MatLab, which may lead to wrong conclusions concerning the operability of PLL-based circuits, are presented.