This document is a survey on power optimization techniques for low power VLSI circuits in deep submicron technology, highlighting the importance of power management due to increasing leakage currents and the necessity to optimize power consumption across various design levels. It discusses key techniques such as voltage scaling, power gating, and use of different threshold voltages, while also outlining the challenges and trade-offs designers face in balancing power, performance, and area. The findings are aimed at helping designers select appropriate techniques based on specific application requirements.