This paper presents a cross-coupled CMOS rectifier for ambient RF energy harvesting, which utilizes an advanced topology amalgamation technique to significantly improve the rectifier’s power conversion efficiency (PCE) and power dynamic range (PDR), also known as the high-PCE range. Our novel technique involves adaptively self-biasing the rectifying PMOS in the last stage of the proposed rectifier, which deactivates the cross-coupled counterpart and enables the subsequent diode-based rectifier circuitry to operate efficiently during high-power operation and extends the high-PCE range by mitigating the leakage current. Fabricated in a 65-nm CMOS process, our proposed rectifier scores a wide PDR of 21 dB at 900 MHz and 15 dB at 1.8 GHz with a peak PCE of 79.77% and 51.3%, respectively, under a 100-kΩ load. Moreover, we perform a Monte Carlo simulation to showcase the impact of transistor variations. Our proposed rectifier, which offers the widest PDR compared to recently-reported designs operating at a similar frequency, is highly adaptable to the varying RF environment, enabling efficient and reliable energy harvesting for Internet of Things devices.