Improved Rectifier Efficiency Using Multi-sine Input Signals

This paper presents the use of multi-tone signals as input signals for an ISM rectifier, that results in improved RF-to-dc efficiency when compared with a single tone signal with the same power. The implementation of a very compact and wideband rectifier allows the use of wideband multi-tone signals, with high number of tones (N up to 8) and wide frequency spacing between adjacent tones. The power distribution of the tones was both uniform and non-uniform. For the implemented rectifier, the highest RF-to-dc efficiency was 65% and was achieved with a 5-tones signal with uneven power distribution. Compared to the 50% recorded RF-to-dc efficiency that was measured for a single tone signal with equal power (0 dBm) a 30% improvement was accomplished.