RFID Rectifier with Backflow Reduction and Bias Preservation
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Solution Overview
Problem
Passive RFID tags face challenges in efficiently converting low-level RF signals into usable voltage due to insufficient RF signal amplitude and intermittent power supply, which affects their operation and memory programming.
Innovation Solution
The implementation of a power rectifier circuit with backflow reduction and bias preservation mechanisms, such as the Dickson RF charge-pump stage and CMOS RF rectifier stages, to maximize energy harvesting and maintain efficient voltage generation despite fluctuations in the RF signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional rectifier circuit is used to convert RF signal to voltage, then the circuit can operate with simple structure, but the conversion efficiency is insufficient due to backflow current and voltage loss
Solution Approach 1:
The rectifier circuit is divided into multiple stages (first rectifier stage, second rectifier stage, third rectifier stage) with each stage performing specific functions. This segmentation allows optimization of each stage for minimal backflow while maintaining overall efficiency, resolving the contradiction between energy efficiency and circuit complexity.
Solution Approach 2:
Bias preservation mechanisms are implemented that maintain optimal bias conditions in advance before the RF signal arrives or during signal interruptions. This preliminary action ensures the rectifier is ready to operate at peak efficiency when the signal returns, reducing energy loss without requiring complex real-time control circuits.
2Power
If charge-pump circuits are used to increase output voltage, then sufficient power can be harvested from low-level RF signals, but the circuit complexity increases and response time is affected
Solution Approach 1:
The Dickson charge-pump stages are merged with the rectifier circuit in a unified multi-stage architecture. This integration allows voltage multiplication and rectification to occur in a coordinated manner, achieving sufficient output voltage while minimizing the overall circuit complexity compared to separate charge-pump and rectifier circuits.
Solution Approach 2:
The charge-pump circuit operates in periodic cycles synchronized with the RF signal envelope, charging capacitors during signal presence and transferring energy during signal interruptions. This periodic operation allows voltage buildup without requiring complex continuous control mechanisms.
3Loss of information
If the RFID tag backscatters to transmit data, then data communication is achieved, but energy harvesting is interrupted causing voltage generation disruption
Solution Approach 1:
Energy is harvested and stored in capacitors during periods when the RF signal is present and the tag is not backscattering. This preliminary energy accumulation ensures that sufficient voltage is available to maintain operation during backscatter intervals, resolving the contradiction between data transmission and power stability.
Solution Approach 2:
The multi-stage rectifier with bias preservation maintains continuous voltage generation by preserving bias conditions across stages during signal interruptions. This ensures that when the tag switches to backscatter mode, the power circuit can maintain operation without disruption, enabling both continuous data transmission and stable power supply.
4Productivity
If multiple rectifier stages are used to improve voltage generation, then energy conversion efficiency increases, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The rectifier is segmented into standardized stages that can be replicated using conventional semiconductor fabrication processes. Each stage uses common components (diodes, capacitors, transistors) with standard layouts, making the multi-stage design manufacturable with existing CMOS or bipolar process technologies despite the increased number of components.
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
These solutions enhance the efficiency of energy conversion, ensuring stable power supply to RFID tags even during intermittent RF signal conditions, thereby improving their operational reliability and memory functionality.
Implementation Method 1
converting the low-level RF waveform to a usable voltage requires a rectifier circuit that can maximize the use of available radiation energy
Data Source
AI summary
The present disclosure provides a power rectifier for a Radio Frequency Identification tag circuit. The power rectifier can be constructed from serially coupled rectifier stages. One of the rectifier stages includes a backflow reduction device or a bias preservation circuit, or both, at least one of which us controlled by a signal derived from a control signal source of the tag circuit.