This paper presents the design, implementation, and evaluation of a miniature rectifier circuit for RF energy harvesting applications. The proposed design aims to give a comprehensive account of the efficiency degradation corresponding to the minimal RF input power less than 0dBm. Our design is based on the optimization of a compact rectifier circuit for capturing the ambient RF power from the wireless applications at frequency 2.45GHz. A co-simulation procedure between electromagnetic (EM) and SPICE simulation have been presented. The circuit shows a simulated RF-DC conversion efficiency of 68% at-10dBm while the measured is 33% at-5dBm. The practical sensitivity of this circuit is very low where the output voltage of 8mV could be detected at RF input signal of-30dBm.A rectifier prototype has been fabricated and tested.