Zigzag Keeper: A New Approach For Low Power Cmos Circuit

Abstract: In CMOS circuits, the reduction of the threshold voltage due to voltage scaling leads to increase in sub threshold leakage current and hence, static power dissipation. For the most recent CMOS feature sizes (e.g., 45nm and 65nm), leakage power dissipation has become an overriding concern for VLSI circuit designers. ITRS reports that leakage power dissipation may come to dominate total power consumption [1]. In the nanometer technology regime, power dissipation and process parameter variations have emerged as major design considerations. These problems continue to grow with leakage power becoming a dominant form of power consumption. Leakage power dissipation is projected to grow exponentially in the next decade according to the International Technology Roadmap for Semiconductors (ITRS).This directly affects portable battery operated devices such as cellular phones and PDAs since they have long idle times. Several techniques at circuit level and process level are used to efficiently minimize leakage current which lead to minimize the power loss and prolong the battery life in idle mode. A novel approach, named “Zigzag keeper,” was proposed at circuit level for the reduction of power dissipation. Zigzag keeper incorporate the traditional zigzag approach with keeper which use the sleep transistor plus two additional transistors driven by already calculated output which retain the state of the circuit during the sleep mode while maintaining the state or state retention.

Keywords: Low Power, Sub-threshold Leakage, Gate oxide Tunneling.