A -28.5-dBm Sensitivity RF Energy Harvesting Interface with 3-D MPPT Achieving > 98% MPPT Accuracy and Good Temperature Consistency

This work presents an RF energy harvesting (RFEH) interface with 3-D hill-climbing (HC) maximum power point tracking (MPPT). For a high sensitivity and good matching consistency over temperature. The 3-D MPPT is achieved by searching the optimal (1) number of rectifier stages, (2) DC-DC input impedance, and (3) shunt input capacitance. We use a constant-energy-packet-extraction(CEPE)-based power sensing scheme for a low quiescent current. Furthermore, we replaced the RF circuit with an ANN model to speed up the simulation. The chip of the prototype $2.4-\mathrm{GHz}$ RFEH was fabricated in a $65-\mathrm{nm}$ CMOS process. It achieved the highest sensitivity $(-28.5 \mathrm{dBm})$ and efficiency $\left(\mathbf{1 0. 4 \%}\right.$ at $\left.-\mathbf{2 0} \mathrm{dBm} P_{\mathrm{IN}}\right)$ among the compared works. And it shows a good performance consistency from −40 to $85^{\circ} \mathrm{C}$, and achieves $\gt 98 \%$ MPPT accuracy within the target $P_{\text {IN }}$ range.