RF Receiver I/Q Correction for Blocker Distortion Cancellation
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Solution Overview
Problem
Existing wireless communication receivers face challenges in effectively canceling blocker signals due to their non-linear response characteristics, which are frequency-dependent and costly to address using complex filtering techniques.
Innovation Solution
A method is implemented in the digital domain to estimate and cancel distortion caused by blocker signals using amplitude-based estimation, independent of frequency shifts, by employing an envelope detector in the analog domain and digital signal processing to generate cancellation coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex filtering techniques are used to cancel blocker signals, then distortion cancellation performance is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces complex analog filtering circuitry with digital signal processing techniques. The distortion cancellation is achieved through digital domain operations including I/Q correction, mixing, and filtering performed by a processor, eliminating the need for specialized high-frequency analog filters and reducing overall device complexity.
Solution Approach 2:
The patent integrates multiple functions into a unified digital signal processing architecture. The same processor and I/Q correction circuitry that perform standard signal processing tasks also handle distortion cancellation, eliminating the need for separate dedicated filtering hardware and reducing device complexity.
2Measurement precision
If frequency-dependent cancellation techniques are used, then distortion cancellation accuracy is improved, but adaptability to frequency shifts deteriorates
Solution Approach 1:
The patent performs I/Q correction and distortion parameter estimation in advance, before the actual signal processing. By pre-characterizing the receiver's non-linear response and storing correction parameters in lookup tables, the system can quickly adapt to frequency shifts without performing complex real-time calculations, thus maintaining both accuracy and adaptability.
Solution Approach 2:
The patent implements a dynamic adaptation mechanism where the distortion cancellation parameters are continuously updated based on the actual received signal characteristics. The system monitors frequency shifts and adjusts the cancellation estimates accordingly, allowing it to adapt to changing conditions while maintaining cancellation accuracy.
3Reliability
If complex cancellation techniques are used, then distortion cancellation effectiveness is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive specialized analog filtering components with standard digital signal processing operations that can be implemented using conventional processors and algorithms. This substitution dramatically reduces component costs while maintaining or improving cancellation effectiveness through software-based adaptive processing.
Solution Approach 2:
The patent uses computationally efficient algorithms that can be implemented with low-cost digital signal processing hardware. By relying on standard processors rather than expensive specialized analog circuits, the system achieves effective distortion cancellation at a fraction of the manufacturing cost of traditional approaches.
Data Source
AI summary
A technique to remove second order and third order nonlinearity distortions caused by a blocker signal at an input of a radio receiver. An envelope detector is utilized at an input of the RF front-end of the receiver to obtain a magnitude of the overall signal. The output of the envelope detector is then processed at baseband to estimate coefficients that relate to the distortion. Once the coefficients are obtained, the coefficients are applied at an I/Q imbalance correction stage to also correct for the distortion by cancelling the distortion from the received signal.