Affiliation:
1. University of Minnesota, USA
2. Intel Labs, USA
Abstract
Well island generation and well tap placement is an important problem in analog/mixed-signal (AMS) circuits. Well taps can only prevent latchups within a certain radius of influence within a well island, and hence must be appropriately inserted to cover all devices. However, existing automated AMS layout paradigms typically defer the insertion of well taps and creation of well islands to a post-processing step after placement. This alters the placement, resulting in increased area and wire length, as well as circuit performance degradation. Therefore, there is a strong need for a solution that generates well islands and inserts well taps
during placement
so the placer can account for well overheads in optimizing placement metrics. In this work, we propose a modular solution using a graph-based optimization scheme that can be used within multiple placement paradigms with minimal intrusion. We demonstrate the integration of this scheme into stochastic, analytical, and designer-driven row-based placement. The method is demonstrated in advanced FinFET technologies. Layouts generated using this scheme show better area, wire length, and performance metrics at the cost of a marginal runtime degradation when compared to the post-processing approach. Using our scheme, there is an average improvement of 3% and 4% and a maximum improvement of 23% and 11% in area and wirelength, respectively, of layouts of various classes of AMS circuits at the cost of 17% average and 29% maximum increase in total runtime.
Publisher
Association for Computing Machinery (ACM)
Subject
Electrical and Electronic Engineering,Computer Graphics and Computer-Aided Design,Computer Science Applications
Reference30 articles.
1. P. Sriram. 2018. Cadence Virtuoso: Doing Placement in a Row-based Environment. Retrieved from https://community.cadence.com/cadence_blogs_8/b/cic/posts/virtuosity-doing-layout-in-a-row-based-environment.
2. Modeling non-slicing floorplans with binary trees
3. Using red-black interval trees in device-level analog placement with symmetry constraints
4. Michel Berkelaar Kjell Eikland and Peter Notebaert. 2004. lp_solve 5.5 Open source (Mixed-Integer) Linear Programming system. Retrieved from http://lpsolve.sourceforge.net/5.5/.
5. BAG2: A process-portable framework for generator-based AMS circuit design