Rectifier Circuit Reduces Power Losses in Contactless RFID Tags
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Solution Overview
Problem
Conventional rectifier circuits for smart cards and RFID tags suffer from high power losses due to threshold voltage requirements and are limited in operating frequency, which hampers efficient power supply and data processing capabilities.
Innovation Solution
The proposed rectifier circuit employs a voltage comparator and current switching units with reference voltage generators to manage voltage differences across terminals, allowing efficient current flow and reverse current interruption at high frequencies, reducing power losses by optimizing the configuration with N-channel and P-channel MOS transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional rectifier circuit using MOS transistors is used, then the circuit can be integrated into CMOS IC chips, but power losses occur due to threshold voltage requirements
Solution Approach 1:
The rectifier circuit is divided into two independent half-wave rectifier circuits (first and second half-wave rectifier circuits) that operate in parallel. Each half-wave rectifier processes one polarity of the AC input signal, allowing both to function simultaneously without interfering with each other's threshold voltage requirements, thereby improving overall efficiency while maintaining CMOS compatibility
Solution Approach 2:
The patent combines two half-wave rectifier circuits into a single full-wave rectifier system that processes both positive and negative cycles of the AC input. By merging these circuits and using a common output node, the system achieves full-wave rectification while maintaining the individual advantages of each half-wave circuit in CMOS implementation
2Productivity
If the operating frequency of the rectifier circuit is increased to enable faster data processing, then data processing speed improves, but power losses increase
Solution Approach 1:
The full-wave rectifier circuit enables continuous power delivery by processing both positive and negative cycles of the AC input signal. This continuous operation eliminates the idle periods present in half-wave rectification, maintaining efficient power conversion at higher frequencies without increasing power losses, thus supporting faster data processing
3Device complexity
If a single half-wave rectifier circuit is used, then the circuit structure is simple, but the other half-cycle of the AC voltage is wasted
Solution Approach 1:
The rectifier system is segmented into two separate half-wave rectifier circuits, each handling one polarity of the AC input. This segmentation allows both half-cycles to be utilized independently and simultaneously, converting the waste problem into an opportunity for parallel operation that improves efficiency while keeping each individual circuit segment simple
Solution Approach 2:
The patent utilizes periodic action by alternating between two half-wave rectifier circuits that operate on successive half-cycles of the AC input. This periodic switching between the two circuits ensures continuous power delivery while maintaining simple circuit structures that can be easily implemented in CMOS technology
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
The solution enables low power losses and high-frequency operation, enhancing the power supply capability of contactless power devices like smart cards and RFID tags, allowing for faster data processing without increased power consumption.
Implementation Method 1
a voltage comparator B1 including a positive input terminal, a negative input terminal, and a comparative output terminal
Implementation Method 2
current switching unit SW0 including source terminal S, drain terminal D, and control terminal G
Data Source
AI summary
The rectifier circuit includes: three terminals A, K, VR; voltage comparator including a positive input terminal, a negative input terminal, and a comparative output terminal; current switching unit including source terminal, drain terminal, and control terminal; first switching unit that conducts or cuts off between source terminal and control terminal of the current switching unit; second switching unit that conducts or cuts off between control terminal of the current switching unit and terminal VR; and reference voltage generator that uses terminal A and terminal VR as input terminals, and includes a voltage output terminal. The voltage output terminal of reference voltage generator is connected to the negative input terminal of the voltage comparator, terminal K is connected to the positive input terminal of voltage comparator, and current flow between first switching unit and second switching unit is exclusively allowed or interrupted by a signal output from the comparative output terminal of voltage comparator).