RFID Transponder Voltage Limiter for Low-Frequency Antenna Protection
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Solution Overview
Problem
Conventional low-frequency RFID transponders require high operating voltage circuit elements to prevent antenna voltage damage, leading to increased costs and complexity.
Innovation Solution
The implementation of nMOS and pMOS limiter circuits that constrain the voltage of the antenna tank circuit signals to predetermined maximum and minimum levels, reducing the need for high operating voltage circuit elements and simplifying the transponder design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high operating voltage circuit elements are used to prevent antenna voltage damage, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces nMOS and pMOS limiter circuits as intermediary components between the antenna tank circuit and the rest of the transponder circuitry. These limiters act as protective mediators that constrain antenna voltage to predetermined maximum and minimum levels, preventing high voltage from reaching sensitive circuit elements without requiring the entire system to operate at high voltage levels.
Solution Approach 2:
The invention changes the operating voltage parameters of the transponder circuitry by using voltage limiting to maintain low operating voltages in sensitive circuits while allowing the antenna to experience higher voltage swings. The nMOS and pMOS limiters dynamically adjust and constrain the voltage parameters, enabling the system to operate reliably across a wide antenna voltage range without requiring high operating voltage circuit elements throughout.
2Reliability
If high operating voltage circuit elements are used to prevent antenna voltage damage, then reliability is improved, but manufacturing cost increases
Solution Approach 1:
The voltage limiter circuits serve as cost-effective intermediary protection devices that enable the use of standard, low-voltage, easily-manufactured circuit elements in the transponder. By placing nMOS and pMOS limiters in series with the antenna tank circuit, the patent allows conventional low-voltage components to be used throughout the transponder design, significantly reducing manufacturing costs compared to using high-voltage rated components throughout the entire system.
3Device complexity
If voltage limiting is implemented, then device complexity is reduced, but the ability to handle wide voltage ranges is constrained
Solution Approach 1:
The patent implements dynamic voltage limiting using nMOS and pMOS transistors that automatically adjust their resistance based on the instantaneous antenna voltage level. These active limiters dynamically constrain the voltage to predetermined maximum and minimum levels during operation, allowing the transponder to adapt to wide antenna voltage ranges while maintaining simple, low-voltage circuit design. The dynamic nature of the limiting enables the system to handle varying voltage conditions without requiring complex switching or regulation circuitry.
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 allows for efficient voltage regulation and protection of transponder circuit elements, reducing costs and improving the reliability of low-frequency RFID systems by maintaining proper operation over a wide antenna voltage range without the need for additional high-voltage components.
Implementation Method 1
nMOS and pMOS limiter circuits that constrain the voltage of the antenna tank circuit signals to predetermined maximum and minimum levels
Implementation Method 2
at least one resonant circuit for receiving a radio frequency signal
Implementation Method 3
a rectifier coupled to the resonant circuit to output a first rectified signal and to output a second rectified signal
Data Source
AI summary
In described examples, an apparatus includes: at least one resonant circuit for receiving a radio frequency signal; a rectifier coupled to the resonant circuit to output a first rectified signal with a constant level portion and a portion matching a first portion of the radio frequency signal, and to output a second rectified signal having a constant level portion and a portion that matches a second portion of the radio frequency signal; a first limiter circuit to limit a voltage of the first rectified signal to a predetermined maximum voltage level; a second limiter circuit to limit the voltage of the second rectified signal to the predetermined maximum voltage level; a third limiter circuit to limit a voltage of the first rectified signal to a predetermined minimum voltage level; and a fourth limiter circuit to limit the voltage of the second rectified signal to the predetermined minimum voltage level.