Adaptive piecewise linear model for class C rectifier design

Abstract

In this work, an adaptive piecewise linear diode model is presented for class C rectifier design. The model is developed based on conventional piecewise linear diode model and curve fitting to extract the model parameters for different input power and load situations. The accuracy of the model is evaluated by comparing the calculated power conversion efficiency (PCE) using the proposed model with the simulation result of a commercial software tool (Keysight's ADS). By using the proposed model, PCE is determined by directly calculating the voltage and current waveforms of the diode using close form equations instead of using ADS harmonic balance simulation. The diode used for this study is SMS7621. With relatively low load resistance, the discrepancy of the calculated PCE compared to ADS is less than 0.0001% (at −0.5 dBm input power and with 1.26 kΩ load). The discrepancy is increased in case of a high load resistance which can be up to 5.28% (at −34.7 dBm input power and 40 kΩ load). The proposed diode model can be used to design a class C rectifier without using a commercial simulator given that the IV curve of the diode is provided in the datasheet or from a direct DC sweep measurement. In addition, the proposed model can also estimate achievable PCE of a diode used for implementation of a class C rectifier.

Estimation of Harvested RF Energy Based on Survey of Ambient RF Power for Optimized Rectifier Design

“…It is noted that the plot in Figure 1 assumes a constant load resistant RL of the rectifier. The effect of the load resistance to PCE is presented in [26] as plots of PCE over RL and in [23] as a PCE contour over the input power and RL. PCE of a rectifier can be maintained over a wide range of RF input power by combining several rectifiers optimized for maximum PCE at different input power levels.…”

“…The level of voltage swing across the diode depends mainly on the DC load and the RF input power. On the diode's IV curve, the voltage swing resulting from the RF input power and the DC load can be plotted as the so-called load line [23]. If the diode is not turned on since the RF input power is too low or the load impedance is too high, the RF to DC conversion does not take place and the PCE drops to zero.…”