RFID Reader Leakage Removing Circuit for Signal Deterioration
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Solution Overview
Problem
RFID systems face signal deterioration and DC offset due to transmission carrier leakage signals, which complicate circuit construction and reduce the effectiveness of receiving signals from RFID tags.
Innovation Solution
A simple circuit construction in the RFID reader that includes a leakage removing circuit with a signal detector, gain amplifier, and phase shifter to sense and convert the transmission carrier leakage signal, allowing it to be synthesized with the received signal and removed, thereby preventing signal deterioration and DC offset.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the transmitting circuit and receiving circuit operate simultaneously at the same frequency, then the RFID reader can communicate with the tag, but the transmission carrier leakage signal directly inputs to the receiving circuit causing signal deterioration and DC offset
Solution Approach 1:
The patent converts the harmful transmission carrier leakage signal into a useful component by using it as the input signal for the canceller circuit. The canceller circuit processes this leakage signal to generate an inverted version that cancels out the original leakage, thereby transforming the harmful interference into a beneficial cancellation mechanism that improves overall signal quality
Solution Approach 2:
The patent introduces a canceller circuit as an intermediary component between the transmitting circuit and receiving circuit. This canceller circuit generates an inverted carrier signal that acts as a mediator to cancel out the leakage signal before it deteriorates the received signal, thus protecting the receiving circuit without affecting the simultaneous operation of both circuits
2Reliability
If a complex canceller circuit is used to remove the transmission carrier leakage signal, then signal quality improves, but the circuit construction becomes complicated
Solution Approach 1:
The patent segments the leakage removal function into distinct modular components: a signal detector for detecting the carrier signal, a gain amplifier for adjusting signal amplitude, and a phase shifter for adjusting signal phase. This segmentation allows each component to perform a specific function independently, simplifying the overall circuit design and making it easier to implement and maintain while effectively removing the leakage signal
Solution Approach 2:
The patent changes the parameters of the transmitted signal by using adjustable gain amplifiers and phase shifters to modify the amplitude and phase of the inverted carrier signal. By dynamically adjusting these parameters to match the detected leakage signal characteristics, the system achieves effective cancellation without requiring complex fixed-circuit designs, thus simplifying the overall circuit construction
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
Effectively attenuates transmission carrier leakage signals, improving signal quality, preventing LNA saturation, and simplifying the RFID reader's circuit construction, while increasing the communication distance and reducing manufacturing costs.
Implementation Method 1
a phase shifter that generates an offset signal by adjusting the phase of the transmitted signal from the gain amplifier so that the phase of the transmitted signal becomes opposite to the phase of the transmission carrier leakage signal
Implementation Method 2
a gain amplifier that converts the amplitude of the transmitted signal from the transmitting circuit
Implementation Method 3
synthesizes the converted signal and the received signal inputted to the receiving circuit
Data Source
AI summary
A radio frequency identification (RFID) reader is provided, having a transmitting circuit that generates a transmitted signal to operate an RFID tag, a receiving circuit that receives a received signal including a tag signal from the RFID tag and a transmission carrier leakage signal leaking from the transmitting circuit, and a leakage removing circuit that senses a phase and amplitude of the transmission carrier leakage signal inputted to the receiving circuit, converts the transmitted signal from the transmitting circuit into a signal having a phase opposite to that of the transmission carrier leakage signal and an amplitude equal to that of the transmission carrier leakage signal, and synthesizes the converted signal and the received signal inputted to the receiving circuit.