RFID Sensor Tags with VCO Impedance Modulation for Simpler Circuits
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Solution Overview
Problem
Existing radio-frequency identification (RFID) technologies require complex semiconductor components, leading to high costs and large sizes due to the need for numerous transistors and intricate connections, which complicates the design and manufacturing process.
Innovation Solution
A sensor system utilizing a reader and a tag with simpler components, including a tag antenna, power harvesting circuitry, and a voltage-controlled oscillator (VCO) to modulate impedance based on sensed parameters, allowing for communication of information without excessive complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If complex semiconductor components are used to enable data communication in RFID systems, then communication functionality is achieved, but component size and cost increase
Solution Approach 1:
The patent extracts the essential communication functionality from complex RFID protocols and implements only the necessary impedance modulation capability in the tag. By removing unnecessary processing functions and keeping only the core impedance modulation mechanism controlled by a simple VCO, the tag achieves communication capability with minimal components, directly resolving the contradiction between functionality and complexity
Solution Approach 2:
The patent employs inexpensive, simple components such as a basic voltage-controlled oscillator (VCO) and passive impedance modulation circuitry in the tag, replacing expensive complex semiconductor components. This approach uses readily available, low-cost components to achieve the required communication function, directly addressing the cost and complexity issues
2Adaptability or versatility
If complex semiconductor components with numerous transistors are used, then processing functionality is provided, but manufacturing cost and device size increase
Solution Approach 1:
The patent extracts only the essential processing functionality needed for impedance modulation and removes all unnecessary processing circuits. The tag uses a simple VCO circuit that requires minimal transistors, eliminating the need for complex semiconductor manufacturing processes and reducing production costs while maintaining the core communication function
Solution Approach 2:
The patent uses a simplified model of communication where the tag merely modulates impedance based on received signals from the reader, copying the essential RFID functionality without implementing full bidirectional complex processing. This approach uses simple circuitry that can be manufactured at low cost while achieving the required processing capability
3Device complexity
If simple mechanisms are used for transmitting information, then component size and cost are reduced, but communication capability may be limited
Solution Approach 1:
The patent implements a feedback mechanism where the reader sends carrier signals to the tag, and the tag modulates its impedance in response, creating a reliable communication loop. The reader detects the impedance changes and interprets them as data, ensuring reliable information transmission despite the simplicity of the tag's transmission mechanism
Solution Approach 2:
The patent uses impedance modulation as an intermediary mechanism to transmit information from the simple tag to the reader. By modulating the electrical impedance of the tag antenna in response to reader signals, the system achieves reliable communication without requiring complex transmission circuitry in the tag, resolving the contradiction between simplicity and reliability
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 and cost-effective communication of sensed parameters by using simpler mechanisms, reducing the need for complex semiconductor technologies and minimizing component size and cost.
Implementation Method 1
a tag antenna configured to receive the carrier signal
Implementation Method 2
power harvesting circuitry coupled to the tag antenna and configured to produce an operating voltage from the received carrier signal
Implementation Method 3
VCO circuitry coupled to the power harvesting circuitry and configured to receive the operating voltage therefrom, wherein the VCO circuitry comprises a VCO configured to generate an output signal having a frequency which varies based on the sensed parameter
Implementation Method 4
the VCO circuitry is configured to modulate an impedance of the tag antenna according to a timing parameter selected based on the frequency of the output signal from the VCO
Data Source
AI summary
A sensor system configured to provide an indication of a sensed parameter, the sensor system comprising: a reader comprising a reader antenna configured to transmit a carrier signal; a tag comprising: a tag antenna configured to receive the carrier signal; power harvesting circuitry coupled to the tag antenna and configured to produce an operating voltage from the receiver carrier signal; the voltage-controlled oscillator, VCO, circuitry coupled to the power harvesting circuitry and configured to receive the operating voltage therefrom, wherein the VCO circuitry comprises a VCO configured to generate an output signal having a frequency which varies based on the sensed parameter, and wherein the VCO circuitry is configured to modulate an impedance of the tag antenna according to a timing parameter selected based on the frequency of the output signal from the VCO; a controller coupled to the reader antenna and configured to: (i) identify an indication of the timing parameter of the impedance modulation of the tag antenna based on detected changes in the reader antenna impedance, and (ii) determine an indication of the sensed parameter based on the identified indication of the timing parameter.