Discontinuous Charge Pump for Ultra-Low Power Harvesting
Solution Overview
Problem
Conventional energy harvesting techniques face efficiency limitations due to continuous charge pump leakage and maximum power point tracking losses, making it challenging to efficiently convert low power from ambient sources like solar cells to battery voltage, especially at ultra-low input levels.
Innovation Solution
A discontinuous energy harvester using a switch-capacitor DC-DC converter operates in two modes: energy harvest and energy transfer, allowing for efficient power accumulation and transfer, reducing leakage and MPPT losses by decoupling the charge pump from power sources during harvesting and coupling it during transfer, thereby optimizing efficiency across a wide range of input powers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional continuous charge pump is used for DC-DC conversion, then power transfer is continuous, but charge pump leakage continuously reduces efficiency
Solution Approach 1:
The patent implements discontinuous periodic operation where the charge pump alternates between active power transfer phases and idle periods. During idle periods, the charge pump is decoupled from power sources, eliminating continuous leakage losses while maintaining periodic power transfer capability.
Solution Approach 2:
The patent extracts the charge pump from continuous connection to power sources by introducing switching mechanisms that decouple the charge pump during idle periods. This separation removes the harmful continuous leakage effect while preserving the useful power transfer function during active phases.
2Power
If charge pump operates continuously, then power transfer is maintained, but leakage losses increase at ultra-low power levels
Solution Approach 1:
The system operates in periodic cycles with active power transfer phases followed by idle periods where the charge pump is switched off or decoupled. This periodic operation maintains average power transfer while eliminating continuous leakage that plagues ultra-low power applications.
Solution Approach 2:
The patent introduces dynamic switching control that adapts the charge pump operation to actual power transfer needs. The system transitions between connected and disconnected states based on harvesting conditions, optimizing the balance between power transfer and leakage reduction.
3Loss of energy
If discontinuous harvesting mode is used, then leakage losses are reduced, but power accumulation time increases
Solution Approach 1:
The discontinuous operation uses periodic active phases to accumulate power rapidly when the charge pump is connected, followed by idle periods for decoupling. This approach trades off continuous operation for reduced leakage while the periodic active phases efficiently accumulate power during connected intervals.
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 extends the harvesting range to sub-nW levels, improving overall efficiency and enabling self-sustaining sensor nodes and IoT devices by trading off efficiency at the source for better performance at ultra-low power levels, achieving up to 37% end-to-end efficiency with minimal input power.
Implementation Method 1
A discontinuous energy harvester using a switch-capacitor DC-DC converter operates in two modes: energy harvest and energy transfer
Data Source
AI summary
Various implementations described herein are directed to an integrated circuit. The integrated circuit may include a charge pump stage having multiple charge storage elements arranged to provide multiple sets of voltages in alternating phases. The integrated circuit may include a voltage multiplexing stage having multiple multiplexers arranged to receive the multiple sets of voltages in the alternating phases. Each multiplexer may provide a selected voltage from the multiple sets of voltages based on a conversion ratio. The integrated circuit may include a voltage summing stage having multiple sampling charge storage elements arranged to receive the selected voltages from each multiplexer and provide an output voltage as a sum of the selected voltages received from each multiplexer.