Yield-aware hierarchical optimization of large analog integrated circuits

Hierarchical optimization using building circuit block pareto performance models is an efficient and well established approach for optimizing the nominal performances of large analog circuits. However, the extension to yield-aware hierarchical methodology, as dictated by the need for safeguarding chip manufacturability in scaled technologies, is completely nontrivial. We address two fundamental difficulties in achieving such a methodology: yield-aware pareto performance characterization at the building block level and yield-aware system-level optimization problem formulation. It is shown that our approach is not only able to effectively capture the block performance trade-offs at different yield levels, but also correctly formulate the whole system yield and efficiently perform system-level optimization in presence of process variations. Our approach extends the efficiency of hierarchical analog optimization, enjoyed for improving nominal circuit performances, to yield-aware optimization. Our methodology is demonstrated by the hierarchical optimization of a phased locked loop (PLL) consisting of multiple circuit blocks.