Cell-Based Semicustom Design of Zigzag Power Gating Circuits

Zigzag power gating (ZPG) has been proposed to overcome the drawback of power gating in its long wakeup delay. However, the use of both NMOS and PMOS current switches in zigzag fashion makes power networks very complicated. This has limited the application of ZPG circuits only to custom design. This paper proposes cell-based semi-custom design of ZPG circuits. A new power network architecture is proposed that allows unmodified conventional logic cells to be used. The circuit elements that supplement the cell-based ZPG design are then discussed. To optimize the physical design of ZPG circuits, two methods are proposed. The area is optimized by modulating the number of different types of circuit rows. The wirelength is optimized by selecting the sleep vector that leads to shorter wirelength between flip-flops and their fanin and fanout gates