Duplexer Impedance Tuning Using Leakage-Based Antenna Matching

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Solution Overview

Problem

Determining the impedance of an antenna in a radio frequency device is difficult, leading to inefficient impedance matching and poor isolation performance between transmitter and receiver, often resulting in unnecessary tuning adjustments.

Innovation Solution

The use of a power detector and post-processing unit to determine transmitter and receiver leakages, combined with a voltage standing wave ratio detector or machine-learning models to estimate antenna impedance, allows for precise impedance tuner settings to be applied, ensuring efficient and accurate matching.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional impedance measurement methods are used to determine antenna impedance, then the measurement process becomes complex and time-consuming, but the impedance matching accuracy improves

Engineering Contradiction:
Improveantenna impedance measurement accuracyVSAvoidmeasurement system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces a machine learning model as an intermediary that processes leakage signals to estimate antenna impedance. Instead of directly measuring impedance through complex traditional methods, the system uses the ML model to infer impedance from easily obtainable leakage data, thereby simplifying the measurement system while maintaining accuracy

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces traditional electrical measurement systems with a machine learning-based estimation system. Rather than using complex impedance measurement circuitry, the system substitutes a computational approach that processes leakage signals through an ML model to determine antenna impedance, reducing hardware complexity

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If frequent impedance tuner adjustments are made to ensure proper matching, then the isolation performance between transmitter and receiver improves, but the system stability deteriorates due to unnecessary tuning adjustments

Engineering Contradiction:
Improveisolation performance between transmitter and receiverVSAvoidtuning system stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent implements a feedback mechanism where the machine learning model continuously monitors leakage signals and dynamically adjusts impedance tuner settings. This intelligent feedback system makes tuning adjustments only when actually needed based on real-time conditions, improving isolation performance while preventing unnecessary adjustments that would destabilize the system

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent introduces dynamic, adaptive impedance tuning based on machine learning predictions. The system transitions from static or frequently-adjusted tuning to dynamic tuning that adapts to changing conditions only when necessary, optimizing isolation performance while maintaining system stability through intelligent timing of adjustments

Inventive Principle:
Principle #15Dynamics

3Device complexity

If simple impedance estimation methods are used, then the system complexity reduces, but the impedance matching accuracy deteriorates

Engineering Contradiction:
Improveimpedance determination system complexityVSAvoidantenna impedance estimation accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent transforms the impedance determination problem by changing the input parameters from direct impedance measurements to leakage signal characteristics. The machine learning model processes these changed parameters (leakage signal magnitude, phase, and temporal characteristics) to accurately estimate antenna impedance, achieving high precision through parameter transformation rather than direct measurement

Inventive Principle:
Principle #35Parameter changes

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 enables efficient and accurate determination of antenna impedance, reducing interference and improving isolation performance by minimizing unnecessary tuning adjustments.

Implementation Method 1

a voltage standing wave ratio detector coupled to the duplexer and the antenna, and a processing circuitry communicatively coupled to the impedance tuner. The voltage standing wave ratio detector determines an antenna impedance at the antenna.

Methodology Applied
Scientific EffectVoltage standing wave ratio: Interference

Implementation Method 2

The processing circuitry applies multiple test impedance settings to the impedance tuner. Moreover, the processing circuitry determines multiple transmitter leakage values and multiple receiver leakage values based on applying the multiple test impedance settings.

Methodology Applied
Scientific EffectPower detection:

Data Source

PatentUS12368429B2Machine-learning based tuning algorithm for duplexer systems
Publication Date: 2025.07.22 APPLE INC
  • US12368429B2 patent drawing
  • US12368429B2 patent drawing
  • US12368429B2 patent drawing

AI summary

This disclosure provides techniques for impedance matching. A radio frequency (RF) device includes a power detector to determine a transmitter leakage and a post-processing unit to determine a receiver leakage, and determines if isolation is acceptable based on the leakages. The RF device may include a device for measuring antenna impedance. Otherwise, the RF device may select multiple tuner settings (e.g., capacitor values) for test signals to be transmitted and received at a target frequency, determine multiple sets of leakage values, determine multiple reflection coefficients based on the multiple sets of leakage values, and determine an estimated antenna impedance at the target frequency based on the reflection coefficients. The RF device then determines impedance tuner settings based on the measured or estimated antenna impedance. Alternatively, the RF device determines impedance tuner settings using an inverse machine-learning model based on a determined matching impedance.