Research And Design Of AC-DC Rectifier Applied In Microwatt System On A Chip

With wireless communication flourishing and light-weight small-size miniaturized systems widely used today, Microwatt computing and self-powered technology have been hot research directions in the field of integrated circuits. To convert AC energy to DC voltage through a rectifier has become increasingly important. Higher the power conversion efficiency is, more power the chip can get. Therefore, AC-DC rectifier circuit with high efficiency has significant research value and broad application prospects. This paper aims to research and design AC-DC rectifier applied in microwatt system on a chip especially at the HF band (13.56MHz).Through the analysis and summary to the operational principle and design theory of the present rectifiers, this paper proposes a new design theory of rectifier-controlled Vth cancellation technique. This technique combines Vth cancellation technique which effectively reduces the forward conduction loss by providing an optimal compensation voltage, and control circuit based technique which effectively reduces leakage current loss by periodically turn-on/off features. Based on this theory, this paper proposes a novel rectifier which realizes high power conversion efficiency and strong output driving capability in lower input power. Based on SMIC 0.18μm standard CMOS process, the proposed rectifier is simulated by Spectre emulator of the Cadence platform. Simulation results show, at 13.56MHz, the PCE of the single-stage,3-stage, and 5-stage rectifiers are 64.8%,56%, and 50.9% with low input power of-18.6dBm,-8.2dBm, and-6.4dBm, respectively. Then the chip’s layout is designed by using Virtuoso layout tools. At last, with partly implementation of near field communication (NFC) system analog front end circuit, the proposed rectifier is verified in this microwatt system on a chip.