A prototype tool for the design-oriented symbolic analysis of analogue circuits

Abstract

New methodologies for the ‘design-oriented’ symbolic analysis of analogue circuits are presented. the objective of this analysis is to obtain results that will give more insight into the circuit behaviour. the feature of the presented methods is to allow the network function to be stated in several parts, with an eventual hierarchical dependence on each other, but without loss of interpretability. Several methods are combined. the first one consists of a rule-based algorithm for network reduction which allows significant simplification before the main analysis is performed. Initially, simple models can be used, since the effects of parasitic elements can be computed afterwards at little CPU expense, thanks to the implementation of the extra element theorem.3 the network is divided into blocks by a simple decomposition algorithm. Each block is analysed and the network function is next calculated. To reduce the size of the calculated expressions, the symbolic calculator uses the concept of ‘correction factor’, based on a comparison between the orders of magnitude of the symbolic terms. A PROLOG prototype tool has been written in order to validate these methods. A simple two-stage amplifier is taken as an example. the solution contains 11 products, to be compared with the 174 that would give a direct topological analysis.