Design of rectenna series-association integrated circuits for radio frequency energy harvesting

What is it about?

Series-connected rectenna associations are proposed to improve the harvesting performance of conventional rectenna circuits by recovering power from different directions. However, the rectenna association performance may be significantly degraded when dealing with different input power levels among rectennas. Therefore, a passive bypass circuit has been added at the output of the series association to short-circuit the weakest rectenna. The proposed design is cost-effective since there is a negligible silicon penalty and no additional power losses.

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Why is it important?

Associating multiple rectifiers in series is a suitable for to increase the output voltage and power. For low input power levels, a single rectifier circuit cannot provide the required voltage and power to the load electronic circuits while the series association of rectennas builds up a higher output voltage from each rectenna, thus increasing the total output power. In addition, it allows increasing the sensitivity of the harvesting circuit (usually a DC/DC converter or a DC voltage regulator follows the rectifier but these circuits require a minimum input voltage of about 400 mV, i.e. the transistor threshold voltage).