A generic topology selection method for analog circuits with embedded circuit sizing demonstrated on the OTA example

FUBOCO: Structure Synthesis of Basic Op-Amps by FUnctional BlOck COmposition

“…The usage of a functional block is either strict (âĂIJconsists ofâĂİ), or a selection of one out of many ("can consist of"). The new composition graph difers from the design plan-based structural synthesis approaches [21,35], which feature a single solution path through such a composition graph based on if-then-else decisions, and from the structural synthesis approaches that use local structural changes with a nearly open-end process. The FUBOCO graph instead provides a large search space of yet only technically meaningful structures and uses a fast equation-based sizing process for an optimization-based selection process.…”

“…A reason for this might be that the current approaches are following two major paths, none of which seems to be attractive from the industrial point of view. One path of structural synthesis is a speciication-based selection of one or few netlists from a library [19,21,[23][24][25]35]. This is an automation of what happens in practice, as every company has a set of, say, 20 to 30 diferent netlists for op-amps, from which is initially chosen according to the speciication.…”

“…Thus, much computation time is spent for circuits which cannot fulill the given speciications from a visual inspection of a designer. Other approaches to lessen the number of created topologies were rule-based topology synthesis algorithms which closely implemented designer knowledge [19,21,25].…”

“…The functional blocks form a composition graph. Thus, it overcomes the topology dependency in [21,24,35]. But it is still close enough to the op-amp structure such that redundant or impracticable topologies are avoided.…”

“…It shows the number of supported topologies, gives an short overview how the topology synthesis is performed and compares the runtime of the algorithms and the used type of sizing. The state-of-the-art synthesis [24] 70 Topology selection from library with subblock templates < 0.2 h Equation-based Gerlach [21] 24 Topology selection from library < 0.5 h Numerical Koza [28] > 10 000 Genetic algorithm based on library with devices w/ or w/o self-connections 2 d Numerical MOJITO-R [36] 3500 Genetic algorithm based on library with devices w/ or w/o self-connections 15 h Numerical Das [12] > 10 000 Graph algorithm on library with devices w/ or w/o self-connections N.a. Numerical Feats [37] > 10 000 Graph algorithm on basic building blocks library 8 h Numerical Zhao [56] 4000 approaches based on equation-based methods to evaluate circuit topologies, e.g., [24,35], use a topology selection method to decide for a topology.…”