針對多重臨界電壓CMOS設計之有效率一筆劃電源開關繞線

Abstract

多重臨界電壓CMOS因能藉由關掉閒置的電路區域而有效率地減少漏電功耗，已成為現今業界最常用的電源閘控技術。然而，被電源閘控下的區域在閒置到工作的模式轉換間可能會消耗大量的瞬間電流。所以主要的IC廠商建議一個接著一個地開啟電源開關以減少模式轉換產生的瞬間電流，故需要漢米爾頓圓環的一筆劃繞線串連所有的電源開關。本論文提出的電源開關繞線架構可有效率地得到一條可行的漢米爾頓圓環繞線以連接電源開關，其不違反兩相連電源開關間的曼哈頓距離限制，同時也能處理因硬體巨集導致電源開關的不規律擺放。此架構可與商業的自動化流程工具相容且已被設計服務公司用於多重臨界電壓CMOS設計的下線。

Multi-threshold CMOS (MTCMOS) is currently the most popular methodology in industry for implementing a power gating design, which can effectively reduce the leakage power by turning off inactive circuit domains. However, large peak current may be consumed in a power-gated domain during its sleep-to-active mode transition. As a result, major IC foundries recommend turning on power switches one by one to reduce the peak current during the mode transition, which requires a Hamiltonian-cycle routing to serially connect all the power switches. The proposed efficient power-switch routing framework, which can effectively and efficiently find a feasible Hamiltonian-cycle routing among power switches without violating the Manhattan distance constraint between any two power switches while handling the irregular placement of the power switches resulting from the hard macros. The proposed framework is compliant to commercial APR tools and has been used in a major design-service company for taping out complex MTCMOS designs.