Analog placement with common centroid constraints

Abstract

In order to reduce parasitic mismatch in analog circuits, some groups of devices are required to share a common centroid while being placed. Devices are split into smaller ones and placed with a common center point. We will address this problem of handling common centroid constraint in placement. A new representation called center-based corner block list (C-CBL) is proposed which is a natural extension of corner block list (CBL) [1] to represent a common centroid placement of a set of device pairs. C-CBL is complete and non-redundant in representing any common centroid mosaic packings with pairs of blocks to be matched. To address the same problem with an additional constraint that devices are required to be placed uniformly to average out the parasitic errors, a grid-based approach is proposed. Experimental results show that both approaches are fast and promising, and have high scalability that even large data sets can be handled effectively.