RFID Receiver Leakage Cancellation via De-rotation
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Solution Overview
Problem
UHF RFID reader systems face significant challenges due to high transmitter leakage into the receiver path, which requires an unusually high dynamic range and is susceptible to nonlinearities, making it difficult to receive weak backscattered signals while transmitting a strong signal at the same frequency.
Innovation Solution
The system includes an RFID reader with a transmitter section, receiver section, control module, and cancellation noise reduction (CNR) section, which generates control signals to de-rotate and subtract leakage signals, using a de-rotation module and quadrature modulator to produce a cancellation signal that reduces interference in the receive path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the receiver section is not well isolated from the transmitter section, then the system structure is simpler, but the transmitter leakage into the receive path increases by up to 110 dB
Solution Approach 1:
The patent extracts the harmful leakage signal from the receive path by generating a separate cancellation signal that is subtracted from the received signal. The CNR section isolates the leakage component and creates an opposing signal to remove it, effectively taking out the harmful factor without requiring complex physical isolation structures.
Solution Approach 2:
The patent applies preliminary anti-action by generating a cancellation signal before the leakage signal interferes with the weak backscattered signal. The de-rotation module and CNR section pre-process the transmit signal to create an anti-phase cancellation signal that neutralizes the leakage before it can overwhelm the receiver.
2Reliability
If a high dynamic range receiver is used to handle transmitter leakage, then the receiver can process strong leakage signals, but the device complexity and cost increase
Solution Approach 1:
The patent converts the harmful leakage signal into a useful cancellation signal. By de-rotating the transmit signal and subtracting it from the receive path, the system transforms the problematic high-power leakage into a beneficial anti-phase signal that actively reduces interference, allowing the use of lower dynamic range receivers.
3Ease of manufacture
If standard cost effective analog signal processing components are used, then the device cost is reduced, but the system becomes susceptible to nonlinearities from the high leakage signal
Solution Approach 1:
The patent introduces an intermediary cancellation signal path that mediates between the transmit and receive sections. The de-rotation module and CNR section act as intermediaries that process the transmit signal to create a cancellation signal, protecting the low-cost analog components from direct exposure to high-power leakage and its nonlinear effects.
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 effectively reduces transmitter leakage by approximately 40 dB, enhancing the dynamic range and improving the receiver's ability to detect weak backscattered signals from transponders, thereby increasing the accuracy and reliability of RFID communications.
Implementation Method 1
a de-rotation module operable to de-rotate, by θ, an in-phase signal and quadrature signal associated with the leakage signal
Implementation Method 2
The CNR section is operable to subtract the reduction signal from the leakage signal
Data Source
AI summary
The present disclosure includes a system and method for adjusting parameters associated with leakage signals. In some implementations, an RFID reader includes an RF antenna, a transmitter section, a receiver section, a control module and a cancellation noise reduction (CNR) section. The transmitter section is coupled to the RF antenna and operable to generate a transmit signal to be transmitted by the RF antenna. The receiver section is coupled to the RF antenna and operable to receive a receive signal from the RF antenna. In addition, the receiver section further includes a de-rotation module and a control module. The de-rotation module is operable to de-rotate, by θ, an in-phase signal and quadrature signal associated with the leakage signal. The control module is operable to generate control signals used to produce a signal for reducing the leakage signal in a receive path of the reader. The CNR section is operable to subtract from the reduction signal from the leakage signal.