Power Harvesting Circuit with Summing Node Diodes
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Solution Overview
Problem
Existing power harvesting systems face inefficiencies when trying to combine energy from multiple antennae due to signal cancellation issues, especially at low power levels, where the output power is often less than the power required to adjust phases or amplitudes, making it difficult to achieve coherent aggregation of power without external energy.
Innovation Solution
A power harvesting circuit design that combines multiple antennae signals within the rectification process using a summing node and diodes to prevent cancellation, allowing for efficient energy harvesting without the need for beam steering or adaptive phase adjustment, utilizing a modified voltage doubling circuit with diodes and capacitors to ensure maximum voltage charging and phase alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If multiple antenna signals are combined before rectification, then the total harvested energy is increased, but signal cancellation occurs at certain phase angles reducing efficiency
Solution Approach 1:
The patent divides the multiple antenna signals into separate rectification paths, with each antenna connected to its own rectifier circuit. This segmentation prevents signal cancellation by avoiding direct summation of RF signals before rectification, while still allowing the rectified DC outputs to be combined for total energy harvesting.
Solution Approach 2:
The patent combines the rectified DC outputs from multiple independent rectifier circuits into a common energy storage capacitor. This merging occurs at the DC level after rectification rather than at the RF level before rectification, thereby preventing signal cancellation while achieving energy aggregation from multiple antennas.
2Loss of energy
If adaptive phase adjustment circuits are added to achieve coherent aggregation, then the energy harvest ratio is improved, but the power consumption exceeds the harvested power at low input levels
Solution Approach 1:
The patent employs passive rectifier circuits that automatically rectify RF signals without requiring active phase adjustment or control circuits. The rectification process itself is self-service, converting RF energy directly to DC energy without consuming additional power for phase synchronization, making it suitable for low-power harvesting applications.
Solution Approach 2:
The patent replaces active electronic phase adjustment mechanisms with passive rectification circuits. Instead of using active components that consume power to adjust phases, the system uses passive diode-based rectifiers that automatically convert RF signals to DC regardless of phase relationships, eliminating the need for power-consuming control circuitry.
3Reliability
If individual rectification is performed for each antenna, then signal cancellation is avoided, but the total harvested power is reduced compared to combined signal rectification
Solution Approach 1:
The patent merges the DC outputs from multiple independent rectifier circuits into a common energy storage capacitor. This allows each rectifier to operate independently on its antenna signal without cancellation issues, while the combined DC outputs aggregate the total harvested power, achieving both efficiency and power maximization.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables efficient energy harvesting from multiple antennae with arbitrary phase differences, avoiding signal cancellation and enhancing the energy harvest ratio, making it suitable for low-power devices like passive RFID tags and sensor nodes.
Implementation Method 1
a power harvesting circuit typically comprises an antenna, a rectifier circuit and an energy storage capacitor
Implementation Method 2
an output capacitor is provided at the output node
Implementation Method 3
Power harvesting relates to the capture of electromagnetic energy from the environment
Data Source
Figure 1
Figure 2A~2B
Figure 3~5
AI summary
A circuit for use in a power harvesting system provides signals from at least first and second antennae to a summing node through respective diodes. The summing node is coupled to an output node through an output diode, and an output capacitor is provided at the output node. This implements combination of antenna signals within a rectification circuit.