Flexible UWB RFID Tag with Printed Battery and Inaccurate Clock
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Solution Overview
Problem
Conventional ultra-wideband (UWB) RFID tags have a large form factor and high cost due to their rigid structure and requirement of a crystal for a clock and frequency source, which cannot be printed or flexibly attached to a thin label, limiting their deployment and increasing manufacturing costs.
Innovation Solution
An active RFID tag implemented as a thin, flexible label with a printed battery, flat antenna, and communication circuit, utilizing an inaccurate clock source based on capacitor charging time, and operating with a low duty cycle to reduce power consumption and achieve UWB communications without a crystal, allowing for flexible attachment and lower production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a crystal is used for clock and frequency source in UWB RFID tags, then timing accuracy is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent removes the crystal component from the RFID tag design entirely. Instead of using a crystal for clock and frequency source, the system relies on the reader's accurate clock to provide timing reference, allowing the tag to operate with simpler circuitry that does not require a crystal oscillator.
Solution Approach 2:
The reader acts as an intermediary that provides the accurate timing reference to the tag. The reader's accurate clock serves as the external timing source that the tag uses for synchronization, eliminating the need for the tag to have its own crystal while maintaining timing accuracy through the reader-mediated timing reference.
2Measurement precision
If a crystal is used for clock and frequency source, then timing accuracy is improved, but ease of manufacture deteriorates
Solution Approach 1:
The crystal component is extracted from the tag design, simplifying the manufacturing process. Without the need to source, mount, and calibrate crystal oscillators, the tag can be manufactured more easily using standard integrated circuit fabrication processes.
Solution Approach 2:
The patent replaces the expensive and complex crystal component with simpler, cheaper circuitry that can be easily manufactured. The system accepts that the tag itself has limited timing accuracy but uses the reader's accurate clock to achieve the required overall system timing precision, allowing for more economical tag construction.
3Adaptability or versatility
If printed battery and flat antenna are used on flexible label, then flexibility and deployment ease are improved, but power consumption management becomes more challenging
Solution Approach 1:
The patent implements periodic communication bursts rather than continuous operation. The tag activates its printed battery and communication circuitry only during scheduled transmission intervals, remaining in a low-power state between bursts. This periodic operation allows the flexible tag with printed components to manage power consumption effectively despite the inherent limitations of printed battery capacity.
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 the mass deployment of UWB tags on flexible labels, reducing power consumption and costs, while maintaining effective communication capabilities, and overcoming design challenges related to accurate timing sources and limited battery capacity.
Implementation Method 1
an inaccurate clock source based on capacitor charging time
Implementation Method 2
the inaccurate clock source is based on the charging time of a capacitor, and typically includes a capacitor and a resistor
Implementation Method 3
a flat antenna printed on the label and a communication circuit implemented in a chip inlay... operating at a center frequency of at least 1 gigahertz and a bandwidth at least twenty percent of said center frequency or a bandwidth at least 500 Mhz
Data Source
AI summary
An active radio frequency identification (REID) tag implemented on a flat label. The tag includes a battery printed on the label, a flat wide-band antenna printed on the label and a wide band communication circuit implemented as a chip inlay inside the label. The circuit is attached to the battery and to the antenna. The combined thickness of the battery, the antenna and the circuit as printed on the flexible label is less than one millimeter. The battery, the antenna and the circuit are printed on the label so as to render substantial flexibility to the RFID tag. The circuit operates at a center frequency of at least one gigahertz and a bandwidth at least twenty percent of said center frequency or a bandwidth at least 500 Mhz. The tag typically includes an inaccurate clock source such as an RC circuit and does not include a crystal. Average power consumption of the battery is preferably reduced by operating the tag with a low duty ratio between an active and an inactive interval; and during the active interval transmitting in bursts while turning off parts of the tag between the bursts. The communications circuit performs timing measurements on incoming received waveforms and transmits transmit signals in response to the received waveforms with timing based on the timing measurements. The receiver circuitry locks on a repetition frequency of the incoming received waveforms, and based on the repetition frequency generates a pulse repetition frequency of the transmit signals.