RF Tag Matching Circuit for Impedance Adjustment Under Unstable Power
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
RF tag circuits face challenges in impedance matching between antennas and RF tag circuits, leading to unstable power supply and inefficient energy transmission due to impedance mismatches caused by changes in antenna impedance, such as metal or dielectric attachments, making it difficult to adjust impedance effectively when the load is not driven.
Innovation Solution
An RF tag circuit configuration that includes a rectification circuit, a matching circuit with variable impedance, a control part, and an adjustment part, which changes the impedance of the matching circuit based on power comparisons before and after the load is activated, allowing for impedance adjustment even during unstable power conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If impedance adjustment is performed when the load is not driven, then the voltage is saturated and the adjustment cannot be properly detected, but if the load is driven during adjustment, then the electric power is unstable and the adjustment period cannot be shortened
Solution Approach 1:
The patent applies preliminary action by measuring the electric power immediately before the load is activated (when voltage is stable) and then using this pre-measured value as a reference for impedance adjustment. This allows the system to perform accurate impedance adjustment without waiting for the unstable period after load activation, effectively resolving the contradiction between measurement accuracy and power stability requirements.
2Reliability
If a load driving period is determined to secure the stabilization time of electric power, then the impedance adjustment can be performed stably, but the load driving period cannot be shortened even when the load can be driven in a shorter time
Solution Approach 1:
The patent performs the electric power measurement action in advance (before load activation) when the system is in a stable state. This preliminary measurement captures the stable power level that would exist after stabilization, eliminating the need to wait for the stabilization period. Consequently, the load driving period can be shortened while maintaining reliable impedance adjustment capability.
Solution Approach 2:
The system uses its own pre-measured electric power data as the reference for impedance adjustment, eliminating the need for external stabilization waiting periods. By serving itself with internally captured stable-state measurements, the system achieves both reliability and time efficiency.
3Reliability
If the impedance of the matching circuit is changed to adjust for antenna impedance variations, then the power supply capability can be improved, but the system complexity increases due to the need for impedance adjustment mechanisms
Solution Approach 1:
The system automatically performs impedance adjustment by comparing pre-measured electric power values with threshold values and autonomously controlling the matching circuit impedance. This self-service approach eliminates the need for complex external impedance adjustment mechanisms while maintaining reliable power supply capability, as the system uses its own measurements to drive the adjustment process.
Solution Approach 2:
The patent implements a feedback mechanism where the measured electric power (taken before load activation) is compared against threshold values, and the result feeds back to control the matching circuit impedance. This automated feedback loop improves power supply capability without requiring complex manual or external adjustment mechanisms.
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 effective impedance adjustment and stable power supply to loads, even when the power is unstable, allowing for efficient energy transmission and operation of RF tag circuits.
Implementation Method 1
a rectification circuit that rectifies a radio wave received by the antenna and supplies DC power
Data Source
AI summary
An RF tag circuit connected to an antenna and a load is provided. The RF tag circuit includes: a rectification circuit rectifying a radio wave received by the antenna and supplying DC power; a matching circuit having a changeable impedance and disposed between the antenna and the rectification circuit; a control part repeatedly controlling activation and stopping of the load; and an adjustment part changing the impedance of the matching circuit in a predetermined direction, storing a first electric power generated by the rectification circuit when a predetermined time has elapsed after the load is activated, and changing the impedance of the matching circuit based on a magnitude relationship between a second electric power generated by the rectification circuit when the predetermined time has elapsed after the load is activated at a timing after the first electric power is generated and the stored first electric power.