Power Management Circuit for IoT Energy Harvesting
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Solution Overview
Problem
Existing power harvesting solutions for IoT devices, such as RFID tags, are inefficient for powering low-power communication devices like BLE devices due to high power consumption and reliance on strong RF signals, which are not designed for battery-powered devices, and cannot effectively utilize parasitic RF signals for energy harvesting.
Innovation Solution
A power management circuit with multiple detectors and a controller that provides multi-level voltage indications to IoT chips, allowing efficient energy harvesting from over-the-air signals and minimizing power consumption by activating only necessary detectors, enabling operation at different voltage levels with low loading DC dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Schmitt trigger based power management unit is used for RFID tags, then the device can operate with strong RF signals (up to 4 Watts), but it consumes high power and cannot efficiently utilize low-power parasitic RF signals
Solution Approach 1:
The power management unit is segmented into multiple detector circuits, each with different reference threshold voltages. This segmentation allows the system to selectively activate only the necessary detectors based on the input signal strength, reducing overall power consumption while maintaining reliable operation across different RF signal levels
Solution Approach 2:
The system dynamically adjusts which detectors are activated based on the voltage level from the energy storage unit. The controller selectively enables or disables detector circuits according to the current operating conditions, optimizing the balance between detection accuracy and power consumption in real-time
2Device complexity
If a single threshold voltage detector is used, then the circuit is simple, but it cannot provide multi-level voltage indications needed for efficient power management of low-power communication devices
Solution Approach 1:
The detection function is segmented into multiple independent detector circuits, each responsible for a specific voltage threshold level. This modular approach provides multi-level voltage indications while keeping each individual detector relatively simple, balancing complexity and functionality
Solution Approach 2:
Multiple detector circuits are designed with the same basic structure but different reference threshold voltages, making them universally applicable for detecting different voltage levels. This multi-functional design allows a single power management unit to handle various operating conditions and voltage states
3Measurement precision
If all detector circuits are always activated, then complete voltage monitoring is available, but power consumption increases significantly
Solution Approach 1:
The system dynamically controls the activation state of each detector circuit based on the current voltage level from the energy storage unit. Only the detectors relevant to the current operating range are activated, maintaining measurement precision while minimizing power consumption by keeping unnecessary detectors in a low-power state
Solution Approach 2:
The controller periodically evaluates the voltage level and selectively activates detector circuits as needed, rather than keeping them continuously active. This periodic activation strategy ensures accurate voltage monitoring is available when needed while reducing average power consumption
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
Enables efficient power management for IoT devices using low-power communication protocols like BLE by harvesting energy from low-power RF signals, reducing power consumption and extending device operation without frequent battery replacements.
Implementation Method 1
The harvester 110 receives RF signals transmitted by a RFID reader (not shown). The energy of the received RF, signals and charges a capacitor 112, where the conversion of energy to current is performed by means of a voltage multiplier 114.
Data Source
AI summary
A power management circuit is provided. The power management circuit includes a plurality of detectors, wherein each of the plurality of detectors are configured with a different reference threshold voltage level; and a controller coupled to the plurality of detectors and configured to activate a subset of the plurality of detectors at any given time, wherein a subset of the plurality of detectors, when activated, are configured to provide a multi-level voltage level indication on a state of a voltage supply.