Variation-Aware Analog Structural Synthesis
This book describes new tools for front end analog designers, starting with global variation-aware sizing, and extending to novel variation-aware topology design. The tools aid design through automation, but more importantly, they also aid designer insight through automation. We now describe four design tasks, each more general than the previous, and how this book contributes design aids and insight aids to each. The ?rst designer task targeted is global robust sizing. This task is supported by a design tool that does automated, globally reliable, variation-aware s- ing (SANGRIA),and an insight-aiding tool that extracts designer-interpretable whitebox models that relate sizings to circuit performance (CAFFEINE). SANGRIA searches on several levels of problem dif?culty simultaneously, from lower cheap-to-evaluate “exploration” layers to higher full-evaluation “exploitation” layers (structural homotopy). SANGRIAmakes maximal use of circuit simulations by performing scalable data mining on simulation results to choose new candidate designs. CAFFEINE accomplishes its task by tre- ing function induction as a tree-search problem. It constrains its tree search space via a canonical-functional-form grammar, and searches the space with grammatically constrained genetic programming. The second designer task is topology selection/topology design. Topology selection tools must consider a broad variety of topologies such that an app- priate topology is selected, must easily adapt to new semiconductor process nodes, and readily incorporate new topologies. Topology design tools must allow designers to creatively explore new topology ideas as rapidly as possible.
A roadmap for analog CAD and its implementation algorithm-by-algorithm, presented by notable figures in analog CAD and analog design field who have experience in both the academia and industryA compelling demonstration of how to overcome a key problem in computational intelligence (genetic programming): trustworthy synthesis of complex structuresA renewed emphasis for analog CAD tools to give insight to analog designers, with many creative examples of new insights providedEach of the tools described show the first-ever approach to solving their respective problem in a fashion that is industrially palatable. Specifically: SANGRIA is the first approach that simultaneously does global and variation-aware analog sizing. CAFFEINE is the first approach for template-free symbolic modeling. MOJITO is the first approach that does trustworthy analog topology synthesis without the need for unreasonable user inputs, and MOJITO-R is the first approach which does it with variation-awareness. The specs-to-topology decision trees are the first which are automatically-constructed. The nonlinear sensitivity analysis is the first-ever approach which includes both structural and sizing parameters. MOJITO-N and ISCLEs are the first approaches to novel topology design which do not have issues with designer trust