Method and apparatus for increasing RF harvesting sensitivity by multi-stage Q-doubler voltages

Abstract

In some embodiments, an apparatus includes an antenna and a rectifier operably coupled to the antenna and configured to receive input power via the antenna. The rectifier can include multiple stages, each of the multiple stages including a tuning network including one or more lumped elements. An initial stage can be configured to receive the input power and generate power based on the input power. Each of the multiple stages coupled to the antenna via at least one previous stage can be configured to receive power from a previous stage and generate a subsequent power associated with (e.g., based on) the power received from the previous stage. The rectifier can be configured to output power associated with a direct current (DC) voltage having a voltage level based on the voltage level associated with the input power.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 437,110, filed January 4, 2023, entitled "Method and Apparatus for Increased RF Harvesting Sensitivity Through Multi-Stage Q-Multiplied Voltage," the disclosure of which is incorporated herein by reference in its entirety. [Background technology]

[0002] Some embodiments described herein generally relate to systems, methods, and apparatus for increasing radio frequency (RF) harvesting sensitivity through multi-stage Q-doubling voltage.

[0003] With the proliferation of the Internet of Things, more electronic devices are being deployed in the world than ever before. These devices operate using some form of energy, typically provided by a small battery or capacitor. Advances in both rechargeable battery and capacitor technology have made it possible to trickle charge these devices with very small amounts of energy, allowing for longer device lifespans when deployed. RF energy harvesting is one approach to achieving this trickle charge effect to supplement the amount of energy stored in electronic devices.

[0004] Given that many RF energy signals, such as ambient RF energy signals, are low power, increased sensitivity of an RF energy harvester is desirable to convert a useful amount of energy that can be used to recharge a device (i.e., increase the amount or level of stored energy in its one or more energy storage elements). Enhanced sensitivity allows lower power RF signals to be converted into usable energy to more effectively recharge the energy storage elements or components of an electronic device (e.g., a wireless device), for example, at greater distances. However, enhanced sensitivity is typically associated with a decrease in the efficiency of the overall RF energy harvesting system.

[0005] Therefore, a need exists for RF energy harvesting methods, devices, and systems that have enhanced sensitivity to RF energy signals and operate efficiently. Summary of the Invention

[0006] In some embodiments, the device includes an antenna and a rectifier. The rectifier may be operably coupled to the antenna and configured to receive input power via the antenna. The rectifier may include multiple stages, each of which includes a tuning network including one or more lumped elements. The multiple stages may include an initial stage configured to receive input power and generate power based on the input power. Each of the multiple stages coupled to the antenna via at least one previous stage may be configured to receive power from the previous stage and generate a subsequent power associated with (e.g., based on) the power received from the previous stage. The rectifier may be configured to output power associated with a direct current (DC) voltage associated with the input power received by the rectifier via the antenna. The voltage level of the DC voltage may be based on the voltage level associated with the input power. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of an RLC circuit, according to one embodiment. [Figure 2] FIG. 2 is a graph 200 illustrating the Q-fold voltage across the capacitor of the RLC circuit shown in FIG. [Figure 3] FIG. 3 is a schematic diagram of an energy harvesting system, according to one embodiment. [Figure 4] FIG. 4 is a schematic diagram of an energy harvesting system, according to one embodiment. [Figure 5] FIG. 5 is a schematic diagram of a variation of the system shown in FIG. 4, according to one embodiment. [Figure 6] FIG. 6 is a schematic diagram of an energy harvesting system, according to one embodiment. [Figure 7] FIG. 7 is a schematic diagram of a variation of the system shown in FIG. 6, according to one embodiment. [Figure 8] FIG. 8 is a schematic diagram of an energy harvesting system, according to one embodiment. [Figure 9] FIG. 9 is a schematic diagram of an energy harvesting system, according to one embodiment. [Figure 10] FIG. 10 is a schematic diagram of an energy harvesting system, according to one embodiment. [Figure 11] FIG. 11 is a schematic diagram of a system including a multi-stage voltage multiplier and a front-end tuning network, according to one embodiment. [Figure 12] FIG. 12 is a schematic diagram of a system including a multi-stage voltage multiplier and inductors such that an inductor-capacitor (LC) tank is included at each harvesting stage, according to one embodiment. [Figure 13] FIG. 13 is a schematic diagram of a system including a multi-stage voltage multiplier and a front-end tuning network, according to one embodiment. [Figure 14] FIG. 14 is a schematic diagram of a system including a multi-stage voltage multiplier and inductors such that an LC tank is included at each harvesting stage, according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] In some embodiments, the device includes an antenna and a rectifier. The rectifier may be operably coupled to the antenna and configured to receive input power via the antenna. The rectifier may include multiple stages, each of which includes a tuning network including one or more lumped elements. The multiple stages may include an initial stage configured to receive input power and generate power based on the input power. Each of the multiple stages coupled to the antenna via at least one previous stage may be configured to receive power from the previous stage and generate a subsequent power associated with (e.g., based on) the power received from the previous stage. The rectifier may be configured to output power associated with a direct current (DC) voltage associated with the input power received by the rectifier via the antenna. The voltage level of the DC voltage may be based on the voltage level associated with the input power.

[0009] In some embodiments, an apparatus includes an antenna, a first tuning network, a first rectifier, a second tuning network, and a second rectifier. The first tuning network may be operably coupled to the antenna and configured to receive radio frequency (RF) power via the antenna and output a first RF power based on the received RF power. The first RF power may have a first voltage level. The first rectifier may be operably coupled to the first tuning network and configured to receive the first RF power and output a second RF power having a second voltage level based on the first voltage level. The second tuning network may be operably coupled to the first rectifier and configured to receive the second RF power from the first rectifier and output a third RF power based on the second RF power. The third RF power may have a third voltage level based on the second voltage level. The second rectifier may be operably coupled to the second tuning network and configured to receive the third RF power and output a fourth RF power having a fourth voltage level based on the third voltage level.

[0010] In some embodiments, an apparatus includes an antenna, a first tuning network, a first rectifier, a second tuning network, and a second rectifier. The first tuning network may be operably coupled to the antenna and configured to receive at least a portion of radio frequency (RF) power received through the antenna and output a first RF power based on the portion of the RF power received at the first tuning network. The first RF power may have a first voltage level. The first rectifier may be operably coupled to the first tuning network and configured to receive the first RF power and output a first multiplied RF power having a second voltage level based on the first voltage level. The second tuning network may be operably coupled to the antenna and electrically coupled in parallel to the first tuning network. The second tuning network may be configured to receive at least a portion of the RF power received through the antenna and output a second RF power based on the portion of the RF power received at the second tuning network. The second RF power may have a third voltage level. The second rectifier may be operably coupled to the second tuning network and configured to receive the second RF power and output a second multiplied RF power having a fourth voltage level based on the third voltage level.

[0011] In some embodiments, an apparatus includes an antenna, a first tuning network, a first rectifier, a second tuning network, and a second rectifier. The first tuning network may be operably coupled to the antenna and configured to receive radio frequency (RF) power via the antenna and output a first RF power based on the received RF power. The first rectifier may be operably coupled to the first tuning network and configured to receive a portion of the first RF power having a first voltage level from the first tuning network and output a first multiplied RF power having a second voltage level based on the first voltage level. The second tuning network may be operably coupled to the first tuning network and configured to receive a portion of the first RF power having the first voltage level from the first tuning network and output a second RF power based on the portion of the first RF power received at the second tuning network. The second RF power may have a third voltage level based on the first voltage level. The second rectifier may be operably coupled to the second tuning network and configured to receive the second RF power and output a second multiplied RF power having a fourth voltage level based on the third voltage level.

[0012] In some embodiments, the RF harvesting system includes multiple harvesting stages to achieve increased front-end sensitivity. Generally, the more stages included in an RF harvesting system, the higher the sensitivity of the RF harvesting system. In some embodiments, the RF harvesting system includes a rectifier (e.g., a multi-stage voltage multiplier circuit such as a multi-stage voltage doubler). To achieve a specific output voltage using a single-stage voltage doubler circuit (also referred to herein as a “voltage doubler”) in an RF harvesting system, the input peak voltage should be half the desired output voltage plus the forward voltage of the rectifying element (e.g., rectifier) ​​of the RF harvesting system. If the RF harvesting system includes two harvesting stages, each including a voltage doubler, the output voltage of the first stage should be half the total output voltage of the two harvesting stages (i.e., half the output of the second harvesting stage). Thus, the input peak voltage to the first harvesting stage should be approximately one-quarter of the total desired output voltage plus any rectifying element voltage drops present. The input power or input peak voltage associated with a specific output voltage of a multi-stage RF harvesting system decreases as more stages are added.

[0013] However, each additional stage reduces the overall efficiency of the multi-stage RF harvesting system due to the associated addition of more rectifying element forward voltage drop losses as each stage is added. For example, when a second stage is added, the RF path has twice the voltage drop contributing to power loss. The system may also have additional inefficiencies due to the presence of longer traces on the printed circuit board (PCB) included in or to which the system is coupled. As more stages are added or included in the RF harvesting system, a point is eventually reached where the power loss is greater than the input power, and the circuit will not rectify no matter how many stages are added.

[0014] The effects of these limitations inherent in RF harvesting systems using multiple harvesting stages can be overcome or reduced by including an inductor-capacitor (LC) tank circuit (also referred to as an LC tank, LC Q-doubler tank, or Q-doubler circuit) within the tuning network to achieve a Q-doubler voltage at the input to each harvesting stage (also referred to as a rectifier stage) of the RF harvesting system. In some embodiments, such a circuit arrangement (e.g., including an LC tank circuit within the tuning network) can also be combined with an approach of including multiple harvesting stages, each of which may or may not have (e.g., may include or be associated with) its own LC tank circuit. This circuit arrangement (e.g., using an LC tank circuit in the tuning network) takes advantage of the reduction in input power or input peak voltage associated with a particular output voltage of the multi-stage harvester and increases the overall sensitivity of the harvester circuit by adding an LC Q-doubler tank at the input to each harvester stage. Where some RF harvesting systems include a tuning network at the input to the RF harvester system, this approach includes a Q-doubler circuit at the input of each stage of the multi-stage RF harvester system.

[0015] RF power harvesting sensitivity is typically limited by the ability of the received RF power to overcome the forward voltage drop of the rectifying device and conduct current through it. The peak voltage at the input to the rectifying device is set by the amount of received RF power and the characteristic impedance of the RF harvesting system. Including an LC tank circuit at the input to the rectifier allows an RF tuning network (also called an RF matching network or tuning network) including an LC tank circuit to resonate at the frequency of the received RF power and generate a Q-multiplied voltage. This allows the peak voltage at the rectifier input to swing to a higher voltage level than would be possible without such an RF tuning network. For example, FIG. 1 is a schematic diagram of a series RLC circuit 100 including a power source 102, a resistor 104, an inductor 106, and a capacitor 108. The following is an equation describing the Q-multiplied voltage across a capacitor at resonance, such as the capacitor in the RLC circuit 100 shown in FIG. 1:

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[0016] FIG. 2 is a graph 200 illustrating the Q-double voltage across the capacitor of the RLC circuit 100 shown in FIG. 1. For example, the Q-double voltage swing shown in FIG. 2 can be more easily overcome by the forward voltage drop of one or more harvester stages (e.g., one or more rectifiers) at lower RF input powers than a non-Q-double voltage network. This technique results in an RF harvesting system with improved harvesting sensitivity. This Q-double voltage can be added to multiple stages of an RF harvester (e.g., by including a Q-double voltage network at the input to each stage), improving overall harvester sensitivity.

[0017] While tuning networks are often included only at the front-end RF input of known multi-stage voltage multiplier circuits, in some embodiments, an RF energy harvesting circuit may include a Q-doubler voltage network coupled between each stage of a rectifier (e.g., a multi-stage voltage multiplier circuit). In some embodiments, a tuning network included in an RF harvesting system that includes a Q-doubler voltage network may include one or more resistors, capacitors, inductors, or any combination of the three in any ratio. In some embodiments, the tuning network may be configured to use the inherent characteristics of one or more harvesters included in the RF harvesting system as part of the tuning network itself, such as the junction capacitance of a diode. Using the tuning network, a Q-doubler voltage may be generated between various stages of the RF harvesting system to obtain a higher peak voltage at the input to one or more rectifier stages. This higher peak voltage allows the forward voltage of the rectifier (also called a rectifying device or rectifying element) to be overcome at a lower input power, thus increasing the sensitivity of the RF harvesting system to the range of power levels of RF signals that can be converted by the RF harvesting system to usable energy. The Q-doubler voltage network may also increase efficiency by reducing impedance mismatch between successive stages of the voltage multiplier.

[0018] In some embodiments, a tuning network, such as any of the tuning networks described herein, may be or include a Q-doubler network. In some embodiments, a tuning network, such as any of the tuning networks described herein, such as a Q-doubler network, may be or include a lumped element network including one or more lumped elements. In some embodiments, the one or more lumped elements may be configured to generate a q-doubler voltage based on the received input power such that the power (e.g., regulated power) generated by each stage is q times the received input power or the power (e.g., regulated power) received by that stage. In some embodiments, one or more lumped elements from the tuning network of an initial stage are configured to impedance match the antenna to a rectifier (e.g., a voltage multiplier circuit such as a voltage doubler). In some embodiments, one or more lumped elements from the tuning network of at least one stage from the multiple stages are configured to bias at least one remaining stage from the multiple stages (e.g., a stage before or after the current stage). In some embodiments, the one or more lumped elements may include at least one parasitic (e.g., a junction capacitance of a rectifying element). In some embodiments, the one or more lumped elements may include a series combination of an inductor and a capacitor (LC). In some embodiments, the one or more lumped elements include an "L" network including an inductor and a capacitor. In some embodiments, the one or more lumped elements include a "Pi" network including a combination of one or more inductors and one or more capacitors.

[0019] In some embodiments, an RF harvesting system may include a Q-doubler network as described herein in conjunction with (e.g., coupled to an input of) a harvester or harvester stage, including, but not limited to, one or more Billard circuits, one or more Greinacher circuits, one or more DeLong circuits, and / or one or more Dickson charge pumps, and one or more half-wave and / or one or more full-wave rectifiers. In some embodiments, an energy harvesting system including a Q-doubler network as described herein can improve the sensitivity of any energy harvesting system configured to harvest RF or AC signals, such as RF energy harvesting, compared to an energy harvesting system without a Q-doubler network.

[0020] In some embodiments, the RF energy harvesting system may include only one voltage multiplication stage. In some embodiments, the RF energy harvesting system may include multiple voltage multiplication stages. In some embodiments, each stage may or may not have its own tuning network and / or Q-multiplication component (e.g., have an input associated with it or coupled to receive an input voltage therefrom). In some embodiments, the RF energy harvesting system may optionally include an overall front-end tuning network (e.g., additional front-end tuning) at the RF input configured to both impedance match the antenna and provide a Q-multiplication voltage to the entire RF energy harvesting system, such as those shown in FIGS. 12-14 .

[0021] In some embodiments, the Q-double component or Q-double voltage network can be located or positioned directly before (e.g., directly electrically coupled to) the input to that stage of the harvesting circuit. In some embodiments, the Q-double component or Q-double voltage network can be located or positioned elsewhere in the circuit (e.g., directly electrically coupled to other components and / or other locations other than the input to the stage, such as the output of one stage or an intermediate stage). In some embodiments, the Q-double voltage network of a subsequent stage can be connected within or after (e.g., directly coupled to) the Q-double voltage network of a previous stage, with the Q-double voltage of the subsequent stage amplifying the already Q-fold voltage of the previous stage. In some embodiments, the input of each harvesting stage can be connected to its own Q-double voltage network, while the output of each harvesting stage can be connected (e.g., electrically coupled) in parallel or series.

[0022] FIG. 3 is a schematic diagram of an energy harvesting system 300. System 300 includes multiple RF tuning networks coupled in a series configuration. As shown, system 300 includes an antenna 310, a first RF tuning network 320, a second RF tuning network 322, a first voltage doubler 330, and a second voltage doubler 332. First RF tuning network 320 is operably coupled to antenna 310 and configured to receive an RF signal including RF power received via the antenna. An output of first RF tuning network 320 is coupled to an input of first voltage doubler 330. An output of first voltage doubler 330 is coupled to an input of second RF tuning network 322. An output of second RF tuning network 322 is coupled to an input of second voltage doubler 332. Second voltage doubler 332 has an output coupled to output 350. Each of first RF tuning network 320 and second RF tuning network 322 may be identical or similar in structure and / or function to any of the tuning networks described herein. For example, one or both of first RF tuning network 320 and second RF tuning network 322 may include a Q-multiplier circuit. Each of first voltage doubler 330 and second voltage doubler 332 may be identical or similar in structure and / or function to any of the voltage doublers described herein.

[0023] As shown, the first RF tuning network 320 may be configured to output a first RF power based on the RF power received from the antenna 310. The first RF power may have a first voltage level. The first voltage doubler 330 may be operably coupled to the first tuning network 320 and configured to receive the first RF power and output a second RF power having a second voltage level associated with (e.g., based on) the first voltage level of the first RF power. The second tuning network 322 may be operably coupled to the first voltage doubler 330 and configured to receive the second RF power from the first voltage doubler 330 and output a third RF power associated with (e.g., based on) the second RF power. The third RF power may have a third voltage level associated with (e.g., based on) the second voltage level. The second voltage doubler 332 may be operably coupled to the second tuning network 322 and configured to receive the third RF power and output a fourth RF power having a fourth voltage level associated with (e.g., based on) the third voltage level. Although described as voltage doublers, in some embodiments, the first voltage doubler 330 and the second voltage doubler 332 may each be a rectifier other than a voltage doubler, e.g., a voltage multiplier other than a voltage doubler. In some embodiments, although not shown, the system 300 may include an RF front-end tuning network operably coupled to the antenna 310 and the first RF tuning network 320. The RF front-end tuning network may be configured to receive RF power from the antenna and transmit the RF power received from the antenna to the first tuning network 320. In some embodiments, the first RF tuning network 320 is configured to generate a Q-multiplied voltage such that the voltage associated with the first voltage level is Q times larger than the voltage associated with the RF power received from the antenna, and the second RF tuning network is configured to generate a Q-multiplied voltage such that the voltage associated with the third voltage level is Q times larger than the voltage associated with the second voltage level.

[0024] 4 is a schematic diagram of an energy harvesting system 400. System 400 includes two RF tuning networks coupled in a parallel configuration, each of the two RF tuning networks coupled to a respective voltage doubler and having a single output. As shown, system 400 includes an antenna 410, a first RF tuning network 420, a second RF tuning network 422, a first voltage doubler 430, and a second voltage doubler 432. System 400 also includes an RF front-end tuning network 440 disposed between antenna 410 and the two tuning networks (i.e., first RF tuning network 420 and second RF tuning network 422). First RF tuning network 420 and second RF tuning network 422 are coupled in parallel such that an input of each tuning network is coupled to an output of RF front-end tuning network 440 and configured to receive the output of RF front-end tuning network 440. The RF front-end tuning network 440 is operably coupled to the antenna 410 and is configured to receive RF signals from the antenna 410 (i.e., received via the antenna 410) and provide the RF signals to the first RF tuning network 420 and the second RF tuning network 422.

[0025] The output of the first RF tuning network 420 is coupled to the input of a first voltage doubler 430. The output of the second RF tuning network 422 is coupled to the input of a second voltage doubler 432. The output of the second voltage doubler 432 is coupled to the input of the first voltage doubler 430. The output of the first voltage doubler 430 is coupled to a system output 450. Thus, the system 400 has a single output 450.

[0026] Each of the first RF tuning network 420 and the second RF tuning network 422 may be identical or similar in structure and / or function to any of the tuning networks described herein. For example, one or both of the first RF tuning network 420 and the second RF tuning network 422 may include a Q-multiplier circuit. Each of the first voltage doubler 430 and the second voltage doubler 432 may be identical or similar in structure and / or function to any of the voltage doublers described herein.

[0027] As shown, in some embodiments, the first RF tuning network 420 may be operably coupled to the antenna 410 and configured to receive at least a portion of the radio frequency (RF) power received via the antenna 410 and output a first RF power based on the portion of the RF power received at the first RF tuning network 420. The first RF power may have a first voltage level. The first voltage doubler 430 may be operably coupled to the first RF tuning network 420 and configured to receive the first RF power and output a first multiplied RF power having a second voltage level related to (e.g., based on and / or greater than) the first voltage level. The second RF tuning network 422 may be operably coupled to the antenna 410 and electrically coupled in parallel to the first RF tuning network 420. The second RF tuning network 422 may be configured to receive at least a portion of the RF power received via the antenna 410 and to output a second RF power based on the portion of the RF power received at the second RF tuning network 422. The second RF power may have a third voltage level. The second voltage doubler 432 may be operably coupled to the second RF tuning network 422 and configured to receive the second RF power and output a second, multiplied RF power having a fourth voltage level related to (e.g., based on and / or greater than) the third voltage level. Although described as voltage doublers, in some embodiments, the first voltage doubler 430 and the second voltage doubler 432 may each be a rectifier other than a voltage doubler, e.g., a voltage multiplier other than a voltage doubler.

[0028] In some embodiments, the RF front-end tuning network 440 may be configured to receive RF power from the antenna 410, transmit a portion of the RF power to the first RF tuning network 420 such that the portion of the RF power received at the first RF tuning network 420 is first front-end RF power, and transmit a portion of the RF power to the second RF tuning network 422 such that the portion of the RF power received by the second tuning network 422 is second front-end RF power.

[0029] In some embodiments, system 400 does not include an RF front-end tuning network. For example, Figure 5 is a schematic diagram of a variation of system 400 shown in Figure 4 without RF front-end tuning network 440. Accordingly, first RF tuning network 420 and second RF tuning network 422 are each configured to receive at least a portion of an RF signal received via antenna 410. Similar to that shown in Figure 4, the two RF tuning networks 420, 422 are coupled in a parallel configuration, each coupled to a respective voltage doubler 430, 432, and system 400 has a single output 450.

[0030] In some embodiments, the first voltage doubler 430 may be operably coupled to the second voltage doubler 432 such that the second voltage doubler 432 is configured to receive the first multiplied RF power from the first voltage doubler 430, and the second multiplied RF power may be based on the second RF power and the first multiplied RF power. The fourth voltage level may be based on a combination of the second voltage level and the third voltage level.

[0031] In some embodiments, an energy harvesting system can include multiple RF tuning networks coupled in a parallel configuration, each RF tuning network coupled to a respective voltage doubler, and the system can include or be configured to be coupled to multiple system outputs. For example, FIG. 6 is a schematic diagram of an energy harvesting system 500. System 500 can be identical or similar in structure and / or function to any of the systems described herein, such as system 400 of FIG. 4, except that system 500 includes or is configured to be coupled to a first system output 550 and a second system output 552 rather than a single system output. For example, system 500 includes an antenna 510, a first RF tuning network 520, a second RF tuning network 522, a first voltage doubler 530, and a second voltage doubler 532. System 500 also includes an RF front-end tuning network 540 disposed between antenna 510 and the two tuning networks (i.e., first RF tuning network 520 and second RF tuning network 522). First RF tuning network 520 and second RF tuning network 522 are coupled in parallel such that the input of each tuning network is coupled to the output of RF front-end tuning network 540 and configured to receive the output of RF front-end tuning network 540. RF front-end tuning network 540 is operably coupled to antenna 510 and configured to receive RF signals from (i.e., received via) antenna 510 and provide the RF signals to first RF tuning network 520 and second RF tuning network 522.

[0032] The output of first RF tuning network 520 is coupled to the input of first voltage doubler 530. The output of second RF tuning network 522 is coupled to the input of second voltage doubler 532. The output of first voltage doubler 530 is coupled to the first system output 550. The output of second voltage doubler 532 is coupled to the second system output 552. Thus, in some embodiments, first voltage doubler 530 can be configured to provide the first multiplied RF power to first system output 550 (also referred to as first device output) independently of second voltage doubler 532, which provides the second multiplied RF power to second system output 552 (also referred to as second device output).

[0033] Each of first RF tuning network 520 and second RF tuning network 522 may be identical or similar in structure and / or function to any of the tuning networks described herein. For example, one or both of first RF tuning network 520 and second RF tuning network 522 may include a Q-multiplier circuit. Each of first voltage doubler 530 and second voltage doubler 532 may be identical or similar in structure and / or function to any of the voltage doublers described herein.

[0034] In some embodiments, system 500 does not include an RF front-end tuning network. For example, Figure 7 is a schematic diagram of a variation of system 500 shown in Figure 6 without RF front-end tuning network 540. Accordingly, first RF tuning network 520 and second RF tuning network 522 are each configured to receive at least a portion of an RF signal received via antenna 510. Similar to that shown in Figure 6, the two RF tuning networks 520, 522 are coupled in a parallel configuration, each coupled to a respective voltage doubler 530, 532, and system 500 has a single output 550.

[0035] FIG. 8 is a schematic diagram of an energy harvesting system 600. System 600 may be identical or similar in structure and / or function to any of the systems described herein, such as system 400 of FIG. 4, except that system 600 may include any suitable number of harvesting stages and / or tuning networks rather than only the two stages shown in FIG. 4. As shown in FIG. 8, each harvesting stage may include an RF tuning network and a voltage doubler. System 600 includes an antenna 610, a first harvesting stage including a first RF tuning network 620 and a first voltage doubler 630, a second harvesting stage including a second RF tuning network 622 and a second voltage doubler 632, and N−2 additional stages, each including an RF tuning network and a voltage doubler. As shown, the final stage N may include an Nth RF tuning network 624 and an Nth voltage doubler 634. Thus, system 600 includes a set of RF tuning networks coupled in parallel to antenna 610. System 600 also includes an RF front-end tuning network 640 disposed between antenna 610 and the set of RF tuning networks (e.g., RF tuning networks 620, 622, 624). Each of the RF tuning networks (e.g., RF tuning networks 620, 622, 624) included in system 600 is coupled in parallel such that an input of each tuning network is coupled to an output of RF front-end tuning network 640 and configured to receive the output of RF front-end tuning network 640. RF front-end tuning network 640 is operably coupled to antenna 610 and configured to receive an RF signal from antenna 610 (i.e., received via antenna 610) and provide the RF signal to first RF tuning network 620 and second RF tuning network 622.

[0036] The output of each RF tuning network from the set of RF tuning networks is coupled to the input of a respective voltage doubler. For example, the output of the first RF tuning network 620 is coupled to the input of the first voltage doubler 630. The output of the second RF tuning network 622 is coupled to the input of the second voltage doubler 632. The output of the Nth RF tuning network 624 is coupled to the input of the Nth voltage doubler 634. The output of the first voltage doubler 630 is coupled to the input of the second voltage doubler 632. The output of the second voltage doubler 632 is coupled to the input of the Nth voltage doubler 634. The output of the Nth voltage doubler 634 is coupled to the system output 650. Thus, the system 600 shown in FIG. 8 has a single output 650.

[0037] Each of the RF tuning networks from the set of RF tuning networks of system 600 (e.g., first RF tuning network 620, second RF tuning network 622, and Nth RF tuning network 624) may be identical or similar in structure and / or function to any of the tuning networks described herein. For example, one, some, or all of the RF tuning networks from the set of RF tuning networks may include a Q-multiplier voltage circuit. Each of the voltage doublers included in system 600 (e.g., first voltage doubler 630, second voltage doubler 632, and Nth voltage doubler 634) may be identical or similar in structure and / or function to any of the voltage doublers described herein.

[0038] As shown, in some embodiments, first RF tuning network 620 may be operably coupled to antenna 610 and configured to receive at least a portion of radio frequency (RF) power received via antenna 610 and output a first RF power based on the portion of the RF power received at first RF tuning network 620. The first RF power may have a first voltage level. First voltage doubler 630 may be operably coupled to first RF tuning network 620 and configured to receive the first RF power and output a first multiplied RF power having a second voltage level related to (e.g., based on and / or greater than) the first voltage level. Second RF tuning network 622 may be operably coupled to antenna 610 and electrically coupled in parallel to first RF tuning network 620. The second RF tuning network 622 may be configured to receive at least a portion of the RF power received via the antenna 610 and to output a second RF power based on the portion of the RF power received at the second RF tuning network 622. The second RF power may have a third voltage level. The second voltage doubler 632 may be operably coupled to the second RF tuning network 622 and configured to receive the second RF power and output a second, multiplied RF power having a fourth voltage level related to (e.g., based on and / or greater than) the third voltage level. Although described as voltage doublers, in some embodiments, the first voltage doubler 630 and the second voltage doubler 632 may each be a rectifier other than a voltage doubler, e.g., a voltage multiplier other than a voltage doubler.

[0039] In some embodiments, as described, first RF tuning network 620 and first voltage doubler 630 are included in a first harvesting stage, second RF tuning network 622 and second voltage doubler 632 are included in a second harvesting stage, and third RF tuning network 624 and third voltage doubler 634 are included in a third harvesting stage. Third RF tuning network 624 may be operably coupled to antenna 610 and electrically coupled in parallel to first RF tuning network 620 and second RF tuning network 622. Third RF tuning network 624 may be configured to receive at least a portion of the RF power received via antenna 610 and to output a third RF power based on the portion of the RF power received at third RF tuning network 624. The third RF power may have a fifth voltage level. The third voltage doubler 634 may be operably coupled to the third RF tuning network 624 and may be configured to receive the third RF power and output a third multiplied RF power having a sixth voltage level associated with (e.g., based on and / or greater than) the fifth voltage level.

[0040] In some embodiments, the first voltage doubler 630 may be operably coupled to the second voltage doubler 632 such that the second voltage doubler 632 is configured to receive the first multiplied RF power from the first voltage doubler 630, and the second multiplied RF power is based on the second RF power and the first multiplied RF power. The fourth voltage level may be based on a combination (e.g., a sum or a function) of the second voltage level and the third voltage level. The second voltage doubler 632 may be operably coupled to the third voltage doubler 634 such that the third voltage doubler 634 is configured to receive the second multiplied RF power from the second voltage doubler 632, and the third multiplied RF power is based on the third RF power and the second multiplied RF power. The sixth voltage level may be based on a combination (e.g., a sum or a function) of the fourth voltage level and the fifth voltage level.

[0041] 8 shows system 600 as having a single system output 650 coupled to voltage doubler 634, in some embodiments, although not shown, each of the voltage doublers in system 600 may include an output coupled or coupleable to a respective system output, similar to that shown for outputs 550 and 552 in FIG. 7. Thus, the voltage doublers in system 600 may not be directly coupled to any other voltage doubler. Thus, system 600 may include multiple system outputs rather than just a single system output 650.

[0042] For example, in some embodiments, the first voltage doubler 630 may be operably coupled to the first device output, the second voltage doubler 632 may be operably coupled to the second device output, and the third voltage doubler 634 may be operably coupled to the third device output such that the first voltage doubler 630 is configured to provide a first multiplied RF power to the first device output independently of the second voltage doubler 632 providing the second multiplied RF power to the second device output, and independently of the third voltage doubler 634 providing the third multiplied RF power to the third device output.

[0043] In some embodiments, an RF front-end tuning network may be directly coupled to only one of the RF tuning networks of a set of RF tuning networks of a system, such that the RF front-end tuning network is disposed between the antenna and that RF tuning network. For example, FIG. 9 is a schematic diagram of an energy harvesting system 700. System 700 includes two RF tuning networks coupled in a parallel configuration, each of the two RF tuning networks coupled to a respective voltage doubler and having a single output. As shown, system 700 includes an antenna 710, a first harvesting stage including a first RF tuning network 720 and a first voltage doubler 730, and a second harvesting stage including a second RF tuning network 722 and a second voltage doubler 732. System 700 also includes an RF front-end tuning network 740 disposed between the antenna 710 and the first harvesting stage (e.g., first RF tuning network 720). RF front-end tuning network 740 is operably coupled to antenna 710 and configured to receive an RF signal from antenna 710 (i.e., received via antenna 710) and provide the RF signal to first RF tuning network 720. Second RF tuning network 722 of the second harvesting stage is coupled to RF front-end tuning network 740 via first RF tuning network 720 of the first harvesting stage.

[0044] The output of the first RF tuning network 720 is coupled to the input of a first voltage doubler 730. The output of the second RF tuning network 722 is coupled to the input of a second voltage doubler 732. The output of the first voltage doubler 730 is coupled to the input of the second voltage doubler 732. The output of the second voltage doubler 732 is coupled to a system output 750. Thus, the system 700 has a single output 750.

[0045] Each of first RF tuning network 720 and second RF tuning network 722 may be identical or similar in structure and / or function to any of the tuning networks described herein. For example, one or both of first RF tuning network 720 and second RF tuning network 722 may include a Q-multiplier circuit. Each of first voltage doubler 730 and second voltage doubler 732 may be identical or similar in structure and / or function to any of the voltage doublers described herein.

[0046] 9 shows system 700 as having a single system output 750 coupled to second voltage doubler 732, in some embodiments, although not shown, first voltage doubler 730 and second voltage doubler 732 may each include an output coupled or coupleable to a respective system output, similar to that shown for outputs 550 and 552 in FIG. 7. Thus, first voltage doubler 730 and second voltage doubler 732 in system 700 may not be directly coupled to one another, and system 700 may include multiple system outputs rather than just a single system output 750.

[0047] In some embodiments, a system can include multiple RF tuning networks (e.g., any suitable number N) coupled in stages, with each RF tuning network including a Q-doubler voltage network being coupled to the system after the previous stage (e.g., after the output of the previous stage). For example, FIG. 10 is a schematic diagram of an energy harvesting system 800. System 800 can be identical or similar in structure and / or function to any of the systems described herein. System 800 can include any suitable number of harvesting stages (e.g., N harvesting stages), with each harvesting stage including an RF tuning network and a voltage doubler. As shown in FIG. 10, system 800 includes an antenna 810, a first harvesting stage including a first RF tuning network 820 and a first voltage doubler 830, a second harvesting stage including a second RF tuning network 822 and a second voltage doubler 832, and N-2 additional stages, each including an RF tuning network and a voltage doubler. As shown, the final stage N may include an Nth RF tuning network 824 and an Nth voltage doubler 834 .

[0048] System 800 also includes an RF front-end tuning network 840 disposed between antenna 810 and a first harvesting stage (e.g., first RF tuning network 820). RF front-end tuning network 840 is operably coupled to antenna 810 and configured to receive an RF signal from antenna 810 (i.e., received via antenna 810) and provide the RF signal to first RF tuning network 820. A second RF tuning network 822 of the second harvesting stage is coupled to RF front-end tuning network 840 via the first RF tuning network 820 of the first harvesting stage, and all subsequent RF tuning networks (e.g., Nth RF tuning network 824) are coupled to RF front-end tuning network 840 via the RF tuning network of a previous harvesting stage that is coupled to RF front-end tuning network 840. Each RF tuning network of a subsequent stage may have an input coupled to an output of the RF tuning network of the previous stage.

[0049] The output of each RF tuning network from the set of RF tuning networks is coupled to the input of a respective voltage doubler. For example, the output of the first RF tuning network 820 is coupled to the input of the first voltage doubler 830. The output of the second RF tuning network 822 is coupled to the input of the second voltage doubler 832. The output of the Nth RF tuning network 824 is coupled to the input of the Nth voltage doubler 834. Furthermore, the output of the first voltage doubler 830 is coupled to the input of the second voltage doubler 832. The output of the second voltage doubler 832 is coupled to the input of the Nth voltage doubler 834. The output of the Nth voltage doubler 834 is coupled to the system output 850. Thus, the system 800 shown in FIG. 10 has a single output 850.

[0050] Each of the RF tuning networks from the set of RF tuning networks of system 800 (e.g., first RF tuning network 820, second RF tuning network 822, and Nth RF tuning network 824) may be identical or similar in structure and / or function to any of the tuning networks described herein. For example, one, some, or all of the RF tuning networks from the set of RF tuning networks may include a Q-multiplier voltage circuit. Each of the voltage doublers included in system 800 (e.g., first voltage doubler 830, second voltage doubler 832, and Nth voltage doubler 834) may be identical or similar in structure and / or function to any of the voltage doublers described herein.

[0051] In some embodiments, for example, the first RF tuning network 820 may be operably coupled to the antenna 810 and configured to receive radio frequency (RF) power via the antenna 810 and output a first RF power based on the received RF power. The first voltage doubler 830 may be operably coupled to the first RF tuning network 820 and configured to receive a portion of the first RF power having a first voltage level from the first RF tuning network 820 and output a first multiplied RF power having a second voltage level related to (e.g., based on and / or greater than) the first voltage level. The second RF tuning network 822 may be operably coupled to the first RF tuning network 820 and configured to receive a portion of the first RF power having the first voltage level from the first RF tuning network 820 and output a second RF power based on the portion of the first RF power received at the second RF tuning network 822. The second RF power may have a third voltage level related to (e.g., based on and / or greater than) the first voltage level. The second voltage doubler 832 may be operably coupled to the second RF tuning network 822 and configured to receive the second RF power and output a second multiplied RF power having a fourth voltage level related to (e.g., based on and / or greater than) the third voltage level. In some embodiments, the first voltage doubler 830 may be operably coupled to the second voltage doubler 832 such that the second voltage doubler 832 is configured to receive the first multiplied RF power from the first voltage doubler 830 and the second multiplied RF power is related to (e.g., based on and / or greater than) the second RF power and the first multiplied RF power (e.g., based on a combination of the second RF power and the first multiplied RF power). The fourth voltage level may be related to (eg, based on and / or greater than) a combination of the second voltage level and the third voltage level.In some embodiments, the first RF tuning network 820 may be configured to generate a Q-multiplied voltage such that the voltage associated with the first voltage level is Q times larger than the voltage associated with the received RF power, and the second RF tuning network 822 may be configured to generate a Q-multiplied voltage such that the voltage associated with the third voltage level is Q times larger than the voltage associated with the first voltage level.

[0052] The third RF tuning network 824 and the third voltage doubler 834 (as well as any additional RF tuning networks and voltage doublers included in the N stages of system 800) may function in relation to the second RF tuning network 822 and the second voltage doubler 832 similarly to how the second RF tuning network 822 and the second voltage doubler 832 function in relation to the first RF tuning network 820 and the first voltage doubler 830. In some embodiments, the RF front-end tuning network 840 may be operably coupled to the antenna 810 and the first RF tuning network 820. The RF front-end tuning network 840 may be configured to receive RF power from the antenna 810 and transmit RF power to the first RF tuning network 820 such that the RF power received by the first RF tuning network 820 is a front-end tuned RF power.

[0053] 10 shows system 800 as having a single system output 850 coupled to voltage doubler 834, in some embodiments, although not shown, each of the voltage doublers in system 800 may include an output coupled or coupleable to a respective system output, similar to that shown for outputs 550 and 552 in FIG. 7. Thus, the voltage doublers in system 800 may not be directly coupled to any other voltage doublers. Thus, system 800 may include multiple system outputs rather than just a single system output 850.

[0054] For example, in some embodiments, the first voltage doubler 830 may be operably coupled to the first device output and the second voltage doubler 832 may be operably coupled to the second device output such that the first voltage doubler 830 is configured to provide a first multiplied RF power to the first device output independently of the second voltage doubler 832 providing a second multiplied RF power to the second device output.

[0055] 11-14 are schematic diagrams of various energy harvesting systems or portions thereof, where the systems include lumped element networks. FIG. 11 is a schematic diagram of system 900, including a multi-stage voltage multiplier 930 and a front-end tuning network 940. FIG. 12 is a schematic diagram of system 1000, including a multi-stage voltage multiplier 1030 and an inductor, such that an LC tank 1020 is included at each harvesting stage. System 1000 also includes a front-end tuning network 1040. FIG. 13 is a schematic diagram of system 1100, including a multi-stage voltage multiplier 1130 and a front-end tuning network 1140. FIG. 14 is a schematic diagram of system 1200, including a multi-stage voltage multiplier 1230 and an inductor, such that an LC tank 1220 is included at each harvesting stage. System 1200 also includes a front-end tuning network 1240.

[0056] Although many of the systems, devices, and methods shown and described herein refer to one or more voltage doublers, in some embodiments, rather than one or more voltage doublers, the systems, devices, and methods described herein may include any suitable rectifier, such as any suitable voltage multiplier. For example, in some embodiments, rather than including one or more of voltage doublers 330 and 332, voltage doublers 430 and 432, voltage doublers 530 and 532, voltage doublers 630, 632, and 634, voltage doublers 730 and 732, and / or voltage doublers 830, 832, and 834, the systems, devices, and methods shown and described herein may optionally be substituted with any suitable rectifier (e.g., a voltage multiplier circuit or another type of rectifier circuit rather than a voltage doubler) configured to perform the functions described herein, such as those described with respect to any of the voltage doublers, rectifiers, and / or voltage multipliers described herein.

[0057] In some embodiments, the methods, systems, and apparatus described herein for achieving a more sensitive harvester circuit (e.g., including an LC tank circuit in the tuning network to achieve a Q-multiplied voltage in one or more stages of voltage multiplication) may be implemented using a method, system, or apparatus described herein, including but not limited to U.S. Patent No. 11,394,246, entitled "Powering Devices Using RF Energy Harvesting," issued on July 19, 2022; U.S. Patent No. 11,245,257, entitled "Method and Apparatus of High Efficiency Rectification for Various Loads," issued on February 8, 2022; U.S. Patent No. 11,418,234, entitled "Bi-Stable Display Tag," issued on August 16, 2022; and U.S. Patent No. 11,418,234, entitled "Methods, Systems, and Apparatus for Automatic RF Power Transmission and Single Antenna Energy Harvesting," issued on November 19, 2019, all of which are incorporated herein by reference in their entireties. No. 10,484,111 entitled "RF-DC Power Converter," issued September 19, 2017; U.S. Patent No. 9,768,711 entitled "RF-DC Power Converter," issued September 19, 2017; and / or U.S. Patent No. 11,368,053 entitled "Methods, Systems, and Apparatus for Wireless Recharging of Battery-Powered Devices," issued June 21, 2022. For example, including a Q-multiplier component in a multi-stage voltage multiplier described herein can be included in a system in parallel with other harvesters tuned for higher input power levels. A higher sensitivity harvester circuit including a Q-multiplier component in one or more stages of a voltage multiplier can provide power at low input power, while a high input power harvester can provide power at high input power. This allows for increased system efficiency while maintaining high system sensitivity.

[0058] In some embodiments, the higher sensitivity designs described herein may be placed in parallel (e.g., electrically coupled) with a radio frequency identification (RFID) integrated circuit (IC), allowing the increased sensitivity of the harvester to bias the RFID IC to increase the read and write range of the RFID IC.

[0059] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Where the methods described above refer to certain events occurring in a particular order, the order of the certain events may be modified. Additionally, some of the events may be performed simultaneously in a parallel process where possible, or may be performed sequentially as described above.

[0060] While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Where the methods described above depict certain events occurring in a particular order, the order of the certain events may be modified. Furthermore, some of the events may be performed simultaneously in a parallel process where possible, or may be performed sequentially as described above.

[0061] In some embodiments, the systems described herein (or any of their components) may include a non-transitory computer-readable medium (which may also be referred to as a non-transitory processor-readable medium) having instructions or computer code thereon for performing various computer-implemented operations. The computer-readable medium (or processor-readable medium) is non-transitory in the sense that it does not itself include a transitory propagating signal (e.g., a propagating electromagnetic wave carrying information over a transmission medium such as space or a cable). The medium and computer code (which may also be referred to as code) may be designed and constructed for a specific purpose. Examples of non-transitory computer-readable media include, but are not limited to, magnetic storage media such as hard disks, floppy disks, and magnetic tape; optical storage media such as compact disks / digital video disks (CDs / DVDs), compact disk read-only memory (CD-ROMs), and holographic devices; magneto-optical storage media such as optical disks; carrier wave signal processing modules; and hardware devices specially configured to store and execute program code, such as application-specific integrated circuits (ASICs), programmable logic devices (PLDs), read-only memory (ROM), and random access memory (RAM) devices.

[0062] Examples of computer code include, but are not limited to, microcode or microinstructions, machine instructions such as those produced by a compiler, code used to generate a web service, and files containing higher-level instructions executed by a computer using an interpreter. For example, embodiments may be implemented using imperative programming languages ​​(e.g., C, Fortran, etc.), functional programming languages ​​(Haskell, Erlang, etc.), logic programming languages ​​(e.g., Prolog), object-oriented programming languages ​​(e.g., Java, C++, etc.), or other suitable programming languages ​​and / or development tools. Further examples of computer code include, but are not limited to, control signals, encrypted code, and compressed code.

[0063] Although various embodiments have been described as having particular features and / or combinations of elements, other embodiments are possible having any feature and / or combination of elements from any of the embodiments, where appropriate.

Claims

1. 1. An apparatus comprising: The antenna and a rectifier operably coupled to the antenna and configured to receive input power via the antenna, the rectifier including a plurality of stages, each stage of the plurality of stages including a tuning network including one or more lumped elements, the plurality of stages including an initial stage configured to receive the input power and generate power based on the input power, each stage of the plurality of stages coupled to the antenna via at least one previous stage configured to receive power from the previous stage and generate a subsequent power related to the power received from the previous stage; 1. The apparatus, wherein the rectifier is configured to output power associated with a direct current (DC) voltage associated with the input power received by the rectifier via the antenna, wherein a voltage level of the DC voltage is based on a voltage level associated with the input power.

2. 2. The apparatus of claim 1, wherein for each stage from the plurality of stages, the one or more lumped elements from the tuning network of the stage are configured to generate a q-fold voltage based on the received input power, such that the power generated by the stage is a q-fold voltage of the received input power or the power received by the stage from the previous stage.

3. The apparatus of claim 1 , wherein the one or more lumped elements from the tuning network of the initial stage are configured to impedance match the antenna to the rectifier.

4. 2. The apparatus of claim 1, wherein at least one of the tuning networks is configured to match an impedance of the antenna to an impedance of a component included in a respective stage associated with the at least one of the tuning networks.

5. 2. The apparatus of claim 1, wherein the one or more lumped elements from a tuning network of at least one stage from the plurality of stages are configured to bias at least one remaining stage from the plurality of stages.

6. The apparatus of claim 1 , wherein the one or more lumped elements include at least one parasitic.

7. 7. The apparatus of claim 6, wherein the at least one parasitic includes a junction capacitance of a rectifier of the stage including the one or more lumped elements.

8. The apparatus of claim 1 , wherein the one or more lumped elements comprise a series combination of an inductor and a capacitor (LC).

9. The apparatus of claim 1 , wherein the one or more lumped elements comprises an “L” network including an inductor and a capacitor.

10. The apparatus of claim 1 , wherein the one or more lumped elements comprise a “Pi” network including a combination of one or more inductors and one or more capacitors.

11. The apparatus of claim 1 , wherein the input power is radio frequency (RF) input power.

12. 1. An apparatus comprising: The antenna and a first tuning network operatively coupled to the antenna and configured to receive radio frequency (RF) power via the antenna and to output a first RF power based on the received RF power, the first RF power having a first voltage level; a first rectifier operably coupled to the first tuning network and configured to receive the first RF power and output a second RF power having a second voltage level based on the first voltage level; a second tuning network operably coupled to the first rectifier and configured to receive the second RF power from the first rectifier and to output a third RF power based on the second RF power, the second RF power having a third voltage level based on the second voltage level; a second rectifier operably coupled to the second tuning network and configured to receive the third RF power and to output a fourth RF power having a fourth voltage level based on the third voltage level.

13. 13. The apparatus of claim 12, further comprising an RF front-end tuning network operably coupled to the antenna and the first RF tuning network, the RF front-end tuning network configured to receive the RF power from the antenna and to transmit the RF power received from the antenna to the first tuning network.

14. 13. The apparatus of claim 12, wherein the first RF tuning network is configured to generate a Q-fold voltage such that a voltage associated with the first voltage level is Q times a voltage associated with the RF power received from the antenna, and the second RF tuning network is configured to generate a Q-fold voltage such that a voltage associated with the third voltage level is Q times a voltage associated with the second voltage level.

15. 13. The apparatus of claim 12, wherein the first rectifier is a first voltage multiplier and the second rectifier is a second voltage multiplier.

16. 1. An apparatus comprising: The antenna and a first tuning network operably coupled to the antenna, the first tuning network configured to receive at least a portion of radio frequency (RF) power received via the antenna and to output a first RF power based on the portion of the RF power received at the first tuning network, the first RF power having a first voltage level; a first rectifier operably coupled to the first tuning network and configured to receive the first RF power and output a first amplified RF power having a second voltage level based on the first voltage level; a second tuning network operatively coupled to the antenna and electrically coupled in parallel to the first tuning network, the second tuning network configured to receive at least a portion of the RF power received via the antenna and to output a second RF power based on the portion of the RF power received at the second tuning network, the second RF power having a third voltage level; a second rectifier operably coupled to the second tuning network and configured to receive the second RF power and to output a second amplified RF power having a fourth voltage level based on the third voltage level.

17. 17. The apparatus of claim 16, further comprising an RF front-end tuning network operably coupled to the antenna, the first RF tuning network and the second RF tuning network, the RF front-end tuning network configured to receive RF power from the antenna, transmit the portion of the RF power received at the first tuning network to the first tuning network such that the portion of the RF power is first front-end RF power, and transmit the portion of the RF power received by the second tuning network to the second front-end RF power.

18. 17. The apparatus of claim 16, wherein the first rectifier is operably coupled to the second rectifier such that the second rectifier is configured to receive the first multiplied RF power from the first rectifier, the second multiplied RF power is based on the second RF power and the first multiplied RF power, and the fourth voltage level is based on a combination of the second voltage level and the third voltage level.

19. 17. The apparatus of claim 16, wherein the first rectifier is operably coupled to the first device output and the second rectifier is operably coupled to the second device output such that the first rectifier is configured to provide the first multiplied RF power to a first device output independently of the second rectifier providing the second multiplied RF power to a second device output.

20. the first tuning network and the first rectifier are included in a first harvesting stage of the device, and the second tuning network and the second rectifier are included in a second harvesting stage of the device, the device comprising:

17. The apparatus of claim 16, further comprising a third harvesting stage including a third tuning network and a third rectifier, the third tuning network operably coupled to the antenna and electrically coupled in parallel to the first tuning network and the second tuning network, the third tuning network configured to receive at least a portion of the RF power received via the antenna and to output a third RF power based on the portion of the RF power received at the third tuning network, the third RF power having a fifth voltage level, and the third rectifier operably coupled to the third tuning network and configured to receive the third RF power and output a third amplified RF power having a sixth voltage level based on the fifth voltage level.

21. 21. The apparatus of claim 20, wherein the first rectifier is operably coupled to the second rectifier such that the second rectifier is configured to receive the first multiplied RF power from the first rectifier, the second multiplied RF power being based on the second RF power and the first multiplied RF power, the fourth voltage level being based on a combination of the second voltage level and the third voltage level; and the second rectifier is operably coupled to the third rectifier such that the third rectifier is configured to receive the second multiplied RF power from the second rectifier, the third multiplied RF power being based on the third RF power and the second multiplied RF power, and the sixth voltage level being based on a combination of the fourth voltage level and the fifth voltage level.

22. 21. The apparatus of claim 20, wherein the first rectifier is operably coupled to the first device output, the second rectifier is operably coupled to the second device output, and the third rectifier is operably coupled to the third device output such that the first rectifier is configured to provide the first multiplied RF power to a first device output independently of the second rectifier providing the second multiplied RF power to a second device output and independently of the third rectifier providing the third multiplied RF power to a third device output.

23. 17. The apparatus of claim 16, wherein the first tuning network is configured to generate a Q-fold voltage such that a voltage associated with the first voltage level is Q times a voltage associated with the portion of RF power received at the first tuning network, and the second tuning network is configured to generate a Q-fold voltage such that a voltage associated with the third voltage level is Q times a voltage associated with the portion of RF power received at the second tuning network.

24. 17. The apparatus of claim 16, wherein the first rectifier is a first voltage multiplier and the second rectifier is a second voltage multiplier.

25. 1. An apparatus comprising: The antenna and a first tuning network operatively coupled to the antenna and configured to receive radio frequency (RF) power via the antenna and to output a first RF power based on the received RF power; a first rectifier operably coupled to the first tuning network and configured to receive a portion of the first RF power having a first voltage level from the first tuning network and to output a first amplified RF power having a second voltage level based on the first voltage level; a second tuning network operably coupled to the first tuning network, the second tuning network configured to receive a portion of the first RF power having the first voltage level from the first tuning network and to output a second RF power based on the portion of the first RF power received at the second tuning network, the second RF power having a third voltage level based on the first voltage level; a second rectifier operably coupled to the second tuning network and configured to receive the second RF power and to output a second amplified RF power having a fourth voltage level based on the third voltage level.

26. 26. The apparatus of claim 25, further comprising an RF front-end tuning network operably coupled to the antenna and the first tuning network, the RF front-end tuning network configured to receive RF power from the antenna and transmit the RF power to the first tuning network such that the RF power received by the first tuning network is a front-end tuned RF power.

27. 26. The apparatus of claim 25, wherein the first rectifier is operably coupled to the second rectifier such that the second rectifier is configured to receive the first multiplied RF power from the first rectifier, the second multiplied RF power is based on the second RF power and the first multiplied RF power, and the fourth voltage level is based on a combination of the second voltage level and the third voltage level.

28. 26. The apparatus of claim 25, wherein the first rectifier is operably coupled to the first device output and the second rectifier is operably coupled to the second device output such that the first rectifier is configured to provide the first multiplied RF power to a first device output independently of the second rectifier providing the second multiplied RF power to a second device output.

29. 26. The apparatus of claim 25, wherein the first tuning network is configured to generate a Q-fold voltage such that a voltage associated with the first voltage level is Q times a voltage associated with the received RF power, and the second tuning network is configured to generate a Q-fold voltage such that a voltage associated with the third voltage level is Q times a voltage associated with the first voltage level.

30. 26. The apparatus of claim 25, wherein the first rectifier is a first voltage multiplier, the second rectifier is a second voltage multiplier, and the third rectifier is a third voltage multiplier.

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