Adaptive subcircuits and compact Verilog-A macromodels as integrated design and analysis blocks in Qucs circuit simulation

Abstract

It is over 20 years since subcircuits were first used in circuit simulation as a means for partitioning parts of an electronic system into identifiable and reusable units. Throughout this period the basic structure of the subcircuit has remained essentially the same. Current developments in open source circuit simulator technology have demonstrated that by merging circuit design algorithms with subcircuit component calculations a new dimension is added to the role played by subcircuits in circuit simulation. This article proposes the embedding of equation-defined algorithms within a subcircuit for circuit design purposes prior to circuit simulation. To illustrate the structure and operation of the new subcircuit extension the design and simulation of an active band-pass filter is described and its performance reported with data obtained from tests using the ‘Quite universal circuit simulator’.