Distortion-Source Mixer for Full-Duplex Linearity

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Solution Overview

Problem

Full-duplex wireless communication systems face challenges due to self-interference, which traditional frequency mixers are unable to address effectively, limiting their performance and spectral efficiency.

Innovation Solution

A system for enhanced linearity frequency mixing, comprising a primary mixer, a distortion-source mixer, signal couplers, a phase shifter, a scaler, and harmonic shorting circuits, which models and subtracts distortion to produce a more linear output without increasing circuit complexity or cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If traditional frequency mixers are used in full-duplex wireless communication systems, then the system can transmit and receive signals simultaneously, but self-interference degrades performance and limits spectral efficiency

Engineering Contradiction:

Improvespectral efficiencyVSAvoidself-interference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent models the distortion generated by the mixer and subtracts it from the output, converting the harmful distortion into a beneficial cancellation effect. The distortion-source mixer intentionally generates distortion that mirrors the primary mixer's distortion, which is then subtracted to cancel the harmful self-interference and improve spectral efficiency

Inventive Principle:

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

Solution Approach 2:

The patent introduces a distortion-source mixer as an intermediary component that generates a distorted version of the input signal. This intermediary signal serves as a template for the distortion present in the primary mixer output, enabling the subtraction process to effectively cancel self-interference while maintaining signal integrity

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If distortion cancellation is implemented using traditional mixer architectures, then linearity may improve, but circuit complexity and cost increase

Engineering Contradiction:

ImprovelinearityVSAvoidcircuit complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent segments the distortion cancellation function into two independent mixer stages: a primary mixer for signal conversion and a distortion-source mixer for distortion generation. This segmentation allows each mixer to be optimized for its specific function while maintaining overall system linearity, avoiding the need for complex single-stage solutions

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the operating parameters of the distortion-source mixer to intentionally generate distorted output that matches the distortion characteristics of the primary mixer. By adjusting LO power levels and mixer bias conditions, the system achieves accurate distortion modeling without requiring complex circuit modifications

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11211969B2Enhanced linearity mixer

Publication Date: 2021.12.28 QUALCOMM INC

AI summary

A system for enhanced linearity mixing includes an input-source signal coupler; a local oscillator (LO) signal coupler; a primary mixer that combines, via heterodyning, the primary-mixer-input signal and the primary-mixer-LO signal to generate a primary-mixer-output signal; a distortion-source mixer that combines, via heterodyning, the distortion-mixer-input signal and the distortion-mixer-LO signal to generate a distortion-mixer-output signal; and an output signal coupler that combines the primary-mixer-output signal and the distortion-mixer-output signal to generate an output signal with reduced non-linearity.