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A Generalized Methodology for Well Island Generation and Well-tap Insertion in Analog/Mixed-signal Layouts

Published: 09 September 2023 Publication History

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.

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  1. A Generalized Methodology for Well Island Generation and Well-tap Insertion in Analog/Mixed-signal Layouts

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      Published In

      cover image ACM Transactions on Design Automation of Electronic Systems
      ACM Transactions on Design Automation of Electronic Systems  Volume 28, Issue 5
      September 2023
      475 pages
      ISSN:1084-4309
      EISSN:1557-7309
      DOI:10.1145/3623508
      Issue’s Table of Contents

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      Association for Computing Machinery

      New York, NY, United States

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      Publication History

      Published: 09 September 2023
      Online AM: 13 March 2023
      Accepted: 10 December 2022
      Revised: 12 November 2022
      Received: 28 July 2022
      Published in TODAES Volume 28, Issue 5

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      Author Tags

      1. Well island generation
      2. well tap sharing
      3. analog circuits
      4. mixed-signal circuits
      5. AMS layout automation
      6. circle graph
      7. Jordan curve

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