Digital PLL Spur Frequency Estimation for Adaptive Cancellation

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Solution Overview

Problem

Existing methods for mitigating spurs in phase locked loops (PLLs) are inadequate, particularly in modern communication systems like 802.11ax, where spur frequencies can change, leading to ineffective spur cancelation due to reliance on preprogrammed expected spur frequencies.

Innovation Solution

A system that estimates spur frequencies based on signals from the PLL, using frequency estimation circuitry to determine the actual spur frequency, which is then used to generate an inverse spur signal for cancellation, allowing for dynamic adjustment to changing operating conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If preprogrammed expected spur frequencies are used for spur cancelation, then the spur cancelation system is simple to implement, but it becomes ineffective when spur frequencies change in modern communication systems

Engineering Contradiction:

Improvesimplicity of implementationVSAvoideffectiveness of spur cancelation

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent implements a dynamic spur frequency estimation mechanism that continuously tracks and adapts to changing spur frequencies in real-time, transforming the static preprogrammed approach into a dynamic system that maintains effectiveness across varying operating conditions in modern communication standards like 802.11ax

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent introduces a feedback loop where the actual spur frequency is estimated from the PLL signal and fed back to adjust the inverse spur signal generation, enabling the system to self-correct and maintain accurate spur cancelation despite frequency variations

Inventive Principle:

Principle #23Feedback

2Measurement precision

If dynamic spur frequency estimation is implemented, then the accuracy of spur cancelation is improved, but the device complexity increases

Engineering Contradiction:

Improveaccuracy of spur frequency estimationVSAvoidcomplexity of frequency estimation circuitry

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent enables the PLL system to self-diagnose and self-correct by estimating its own spur frequency from its internal signals and automatically adjusting the cancelation mechanism, eliminating the need for external calibration equipment or complex manual tuning procedures

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent changes the operational parameters of the spur cancelation system by dynamically adjusting the inverse spur signal based on estimated frequency variations, allowing the system to adapt to different operating conditions without requiring complete redesign for each scenario

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10873333B2Spur frequency estimation inside digital phase locked loop

Publication Date: 2020.12.22 INTEL CORP

AI summary

Systems and methods configured to cancel spurs in a phase locked loop (PLL) system are provided. A method configured to cancel spurs in a PLL system includes receiving a PLL signal from the PLL system; determining an estimated spur frequency of a spur in the received PLL signal based on the received PLL signal; and canceling the spur in the received PLL signal based on the estimated spur frequency.