Optimal Operation of Multitone Waveforms in Low RF-Power Receivers

This paper presents a study of the optimal performance of multitone signals in low RF-power transfer and energy harvesters. The choice of the load can be tricky, showing an advantage of a certain type of signals over another. For low RF power (-17dBm), the multitone signals do not improve the peak RF-to-dc power conversion efficiency (PCE) over the continuous wave (CW) single-tone signal, if the optimal load is selected for each case, however, the multitone signals maintain that peak PCE of ~ 47% over higher output voltage (i.e: larger loads), and consequently enable more efficient dc-to-dc voltage boosting or even eliminate the need for the voltage booster in the RF power receiver. Thus, the low-power multitone waveforms can be considered as a voltage sensitivity booster rather than a PCE efficiency booster. This boosted rectified voltage is the key advantage of the multitone signals that leads to the enhancement in the overall efficiency of the low-RF power receiver.