Rectifying circuit for multiband radio frequency (RF) energy harvesting

A radio frequency (RF) energy harvesting system including a plurality of RF energy harvesting devices, each RF energy harvesting device comprising:

• an antenna including a first antenna end point, a second antenna end point, and at least one elongated conductive structure connected to the first and second antenna end points and configured to resonate at RF frequencies within an associated bandwidth range;
• and
• a rectifying circuit including:
• a first diode coupled between the first antenna end point and a first node;
• a first capacitor coupled between the second end point and the first node;
• a second diode coupled between the first node and a second node, wherein the first diode has a lower forward voltage than the second diode, and the first diode has a lower peak inverse voltage than the second diode;
• and
• an output control circuit coupled between the second node and an output node, said output control circuit being configured to convert a second intermediate voltage generated on the second node into a direct current (DC) output voltage, and
• wherein the plurality of RF energy harvesting devices are coupled together to generate a combined system output voltage.

A radio frequency (RF) energy harvesting device comprising:

• a flexible substrate;
• an antenna including at least one elongated antenna structure conformally disposed on said flexible substrate and configured to resonate at RF frequencies within an associated bandwidth range, said antenna including a first antenna end point and a second antenna end point;
• and
• a rectifying circuit including:
• a plurality of conductive line segments conformally disposed on said flexible substrate;
• a first diode coupled by way of a first said conductive line segment to the first antenna end point;
• a first capacitor coupled by way of a second said conductive line segment to the second antenna end point;
• a second diode coupled to the first capacitor and to the first diode by way of a third said conductive line segment,
• wherein the first diode has a lower forward voltage than the second diode, and the first diode has a lower peak inverse voltage than the second diode.