針對粗顆粒多重臨界電壓CMOS技術之電源開關繞線

Abstract

多重臨界電壓CMOS (MTCMOS) 是一種有效的電源閘控制設計技術，藉由適當的交互使用高臨界電壓與低臨界電壓裝置，同時減低晶片之漏電流功率消耗，並維持晶片所需之表現。然而，現有的文獻當中，並無太多對於MTCMOS技術在後段工具演算法上的討論，而現階段EDA供應廠商，對於MTCMOS技術的支援也還是不夠完整。 在這個計畫當中，我們要針對TSMC所使用的粗顆粒MTCMOS技術，設計一個MTCMOS開關繞線的軟體。這個開關繞線軟體的目標包含以下三點，第一，找到一條可行的漢米爾頓路徑 (Hamiltonian path) ，並包含所有的MTCMOS開關，這樣所產生之回應訊號，可以保證所有的MTCMOS開關都有被打開；第二，要讓所有的MTCMOS開關之間的連線，都滿足預設的曼哈頓距離 (Manhattan distance)限制，這樣所產生的MTCMOS開關之輸出負載，可以保證小於時間函數庫 (timing library) 所設定之上線；第三，將總繞線長度降到最低，這樣所產生之繞線負擔，以及喚醒(wake-up)/回應(acknowledge)訊號之回應時間，都可以被最小化。此外，所提出之MTCMOS開關繞線軟體，必須能夠融入現有之後段設計流程中。

Multi-threshold CMOS (MTCMOS) is an effective power-gating technique to simultaneously reduce IC’s leakage power consumption and maintain IC’s high performance by properly using high-Vt and low-Vt devices. However, few existing literatures have discussed the algorithms required in MTCMOS’s back-end tools, and the current tool support from the EDA vendors is not sufficient yet. In this project, we would like to propose a framework for MTCMOS switch routing based on the coarse-grain MTCMOS technologies provided by TSMC. The objective of this switch-routing framework is to (1) find a feasible Hamiltonian path covering all MTCMOS switches, such that its resulting acknowledge signal can guarantee the turn-on of all MTCMOS switches, (2) keep all connections between MTCMOS switches under the Manhattan-distance constraint, such that the output loading of a MTCMOS switch will not exceeds the constraint of its timing library, and (3) minimize the total routing length, such that the routing overhead as well as the response time of the wake-up/acknowledge signals can be minimized. Furthermore, the proposed MTCMOS switch-routing needs be compatible to the current design back-end flow.