Inverse Spur Injection for RF Transceiver Spur Cancellation

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Solution Overview

Problem

Existing transceiver systems suffer from spurs generated by non-linearities in RF components, which degrade performance and violate regulatory requirements, and conventional RF techniques for mitigation often fail to adequately attenuate spurs without degrading the wanted signal.

Innovation Solution

The system generates an inverse spur signal that matches the expected spur in terms of gain and phase, which is injected into the transceiver signal chain to cancel out the spur, using digital processing techniques to determine the inverse spur signal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional RF techniques (e.g., RF/analog notch filtration) are used to attenuate spurs, then spur attenuation is achieved, but the wanted signal is also degraded due to filtration

Engineering Contradiction:
Improvespur attenuationVSAvoidwanted signal quality
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent generates an inverse spur signal that mimics the characteristics of the unwanted spur (frequency, amplitude, phase) and injects it into the signal chain to cancel the harmful spur through destructive interference. This converts the harmful spur into a beneficial cancellation mechanism, achieving spur attenuation without degrading the wanted signal as conventional filtration would do

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The system performs preliminary analysis to identify spur characteristics (frequency, gain, phase) and pre-generates the inverse spur signal before injection. By preparing the counteracting signal in advance with the correct parameters, the system eliminates spurs before they can significantly degrade the wanted signal, rather than attempting to filter them out after the fact

Inventive Principle:
Principle #9Preliminary anti-action

2Productivity

If RF components operate with non-linearities, then signal processing functionality is achieved, but spurs are generated that degrade transceiver performance

Engineering Contradiction:
Improvesignal processing capabilityVSAvoidspur generation
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent implements a feedback mechanism where the signal chain is monitored to identify generated spurs, and the characteristics of these spurs (frequency, gain, phase) are used to generate the corresponding inverse spur signal. This closed-loop feedback system continuously counteracts spurs generated by non-linear RF components, allowing the system to maintain signal processing functionality while eliminating the harmful effects of non-linearity

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The inverse spur signal acts as an intermediary element that mediates between the harmful spurs generated by non-linear RF components and the wanted signal. By introducing this intermediate cancellation signal, the system allows the non-linear components to continue functioning while their harmful output is neutralized through the intermediary inverse spur

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3590197B1Spur cancelation using inverse spur injection
Publication Date: 2025.09.10 APPLE INC
  • EP3590197B1 patent drawingFigure 1~2
  • EP3590197B1 patent drawingFigure 3
  • EP3590197B1 patent drawingFigure 4

AI summary

A spur cancelation system includes error circuitry, inverse spur circuitry, and injection circuitry. The error circuitry is configured to generate an error signal based at least on a first transceiver signal in a transceiver signal processing chain. The inverse spur circuitry is configured to, based at least on the error signal, determine a gain and a phase of a spur signal in the transceiver signal and generate an inverse spur signal based at least on the gain and the phase of the spur signal. The injection circuitry is configured to inject the inverse spur signal to cancel a spur in a second transceiver signal in the transceiver signal processing chain.