Frequency Switching Dual Power Band Rectifier with Load-Modulation Technique

The frequency switching dual power band rectifier is proposed to achieve both low-power and high-power applications from a single circuit. Two different operating frequencies f(1) = 900 MHz and f(2) = 2.4 GHz are selected for lowpower and high-power applications, respectively. The proposed rectifier fulfills stable operation at two levels of input power by making frequency switching. The Schottky diodes HSMS 2850 and HSMS 2860 are selected for f(1) and f(2), respectively, based on their performance with respect to the input power. Instead of conventional lumped inductors, defected ground structure (DGS)-based inductors are employed in matching circuits. For maximum RF-to-dc conversion efficiency in both low and high-power conditions, two different optimal loads are required, which is achieved from the load-modulation technique by using Bipolar Junction Transistor (BJT). The measurement result of the proposed rectifier shows more than 50% conversion efficiency for the power range -18 dB to 2 dBm and 8 dBm to 20 dBm with circuit size of 35 mm x 30 mm.