[[alternative]]A Flip-Flop Replacement Technique for Peak Current Reduction

碩士電子工程學系[[abstract]]隨著製程進步以及晶片功能需求日益複雜，單位面積的電晶體(Transistor)數量比例急劇提昇，電路中同步觸發(Simultaneous Switching)的電晶體數目也將隨之增加，超深次微米(Ultra Deep Sub-Micron)電路有著許多的問題仍需克服挑戰，如它會瞬間產生巨大的尖峰電流，造成電遷移（Electro Migration）、晶片的自熱（Self-Heat）、電壓源下降（IR Drop）與接地彈跳（Ground Bounce）等問題，這些問題會嚴重的影響晶片的壽命、可靠度（Reliability）及電路的執行速度與訊號的準確性。 在正緣時脈觸發的同步電路中，尖峰電流往往就是出現在時脈上升緣的時候，使的組合電路同時轉換而產生巨大的尖峰電流，因此我們設計了三組不同傳輸時間的新型延遲正反器（Delay Flip-Flops），用它們去更換原先不是在臨界路徑(Critical Path)上的Flip-Flop，好讓Flip-Flop所驅動的組合電路Switching時間可以錯開，如此一來，便可以降低整體電路的尖峰電流，所以IR Drop的問題也可以得到舒緩。 在本論文當中，我們會提出尖峰電流最佳化的技術與演算法，在一個充滿眾多Flip-Flops的電路中，快速挑選適當的Flip-Flops來代換，使得尖峰電流得以有效的減少。 關鍵字：超深次微米，尖峰電流，電遷移，自熱，電壓源下降，接地彈跳，臨界路徑。[[abstract]]As process technology progresses to ultra deep sub-micron, the number of transistors in unit's area is promoted sharply. The number of transistors that simultaneous switching also increase in the circuit. There are many issues that need to challenge in the ultra deep sub-micron circuit, such as the enormous peak current. The enormous peak current will cause the problems, such as electro migration, self-heat in chip, IR drop and ground bounce. They influence the lifespan and the reliability of the chip seriously. They also affect the speed of the execution and accuracy of the signal in the circuit. A huge peak current is observed at each clock rising edge due to the combination circuit simultaneous switching in a high-speed synchronous digital system. We design three groups of the new-type delay flip-flops with different transmission time. We replace selected normal flip-flops not in critical path of a circuit by the new-type delay flip-flops, so the replacement causes the switching times of flip-flops to be separated. Thus it can reduce the peak current and IR drop effect in the circuit. In this thesis, we propose the peak current optimization technology and the algorithm that find the suitable flip-flops in the circuit and then replace them by the new-type delay flip-flops. After the process of the algorithm, the peak current of the circuit can be effective reduced. Key word: ultra deep sub-micron, peak current, electro migration, self-heat, IR drop, ground bounce, critical path