A highly-integrated CMOS power-management system with wide-range RF for ultra-high frequency (UHF) wireless energy harvesting is presented. To avoid environment-caused sudden power loss and to scavenge energy efficiently, the proposed power management system adopts power-aware rectifier architecture and adaptive DC-DC conversion ratios according to the input power level. The proposed system was fabricated in a 0.18-μm CMOS process. The system achieved a peak RF/DC conversion efficiency of 59%, a sensitivity of -11.6dBm, and a 13.5dB RF input range for at least 20% power efficiency at a 100KΩ load. At the high input power region (>-9dBm), the proposed architecture improves about 15% efficiency when compared to a conventional rectifier followed by a linear regulator. The peak efficiency of the entire system is 37%.