Nonlinear Circuit Simulation by Means of Alfred Fettweis' Wave Digital Principles

A dependable circuit simulation plays an elementary part in the process of commercial circuit design. However, when Alfred Fettweis invented the concept of Wave Digital Filters (WDFs) back in the early 1970s, that was clearly not the case as tools like SPICE hadn't been published yet. But even though Fettweis' new WDFs were able to provide an accurate digital model of analogue reference circuits, they were mostly perceived as an elaborated technique for digital filter design. In this article we provide an insight into Wave Digital Filters with a focus on nonlinear circuit simulation, highlighting assets and drawbacks of the method. In particular, recent results that extend the Wave Digital concept towards a general circuit simulation strategy with interesting properties are presented.