Multiphase RTWO Mixer for Low-Power RF Down Conversion

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Solution Overview

Problem

Existing radio frequency mixer technologies face limitations in generating multiple phases with good spectral purity and low power consumption, particularly for applications requiring multiple phases simultaneously, such as wireless systems with modern digital modulation, where ring oscillators are limited by time delay and power consumption.

Innovation Solution

A multiphase mixer utilizing a rotary traveling wave oscillator to generate multiple phases at a lower frequency, allowing for direct-conversion of high frequency signals with a local oscillator, which reduces LO leakage and power consumption by mathematically equivalent conversion of single phase high frequency signals into multiphase reduced frequency signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a ring oscillator is used to generate multiple phases, then multiple phases can be obtained, but the time delay is limited by the inverter delay and power consumption increases

Engineering Contradiction:

Improvenumber of phasesVSAvoidpower consumption

Core Design Contradiction:

Quantity of substanceVSUse of energy by moving object

Solution Approach 1:

The patent replaces the traditional ring oscillator (based on inverter delay) with a rotary traveling wave oscillator that uses transmission line phase propagation. This substitution eliminates the need for multiple inverters per phase, significantly reducing power consumption while maintaining the ability to generate multiple phases simultaneously.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the fundamental parameter of phase generation from time-delay-based (ring oscillator) to transmission-line-based (rotary oscillator). By using the electrical length of transmission lines instead of inverter propagation delays, the system achieves lower power consumption and better spectral purity while generating N phases.

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If a ring oscillator is used to generate multiple phases, then multiple phases can be obtained, but the spectral purity deteriorates

Engineering Contradiction:

Improvenumber of phasesVSAvoidspectral purity

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent replaces the ring oscillator's inverter-based phase generation with a rotary traveling wave oscillator using transmission lines. This substitution provides superior spectral purity because transmission lines offer more controlled impedance and better phase matching, reducing spurious signals and improving the quality of generated phases.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Quantity of substance

If multiple oscillators are injected together to generate multiple phases, then the required phases can be obtained, but the device complexity increases

Engineering Contradiction:

Improvenumber of phasesVSAvoidcircuit complexity

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent merges multiple phase generation into a single rotary traveling wave oscillator circuit. Instead of using multiple separate oscillators that need to be injected and synchronized, the invention generates all N phases simultaneously in one integrated circuit, significantly reducing device complexity while maintaining the required number of phases.

Inventive Principle:

Principle #5Merging (Combining)

4Manufacturing precision

If a standard LC tank solution is used, then good spectral purity can be achieved, but power consumption increases

Engineering Contradiction:

Improvespectral purityVSAvoidpower consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent replaces the traditional LC tank oscillator with a rotary traveling wave oscillator based on transmission lines. This substitution maintains good spectral purity through controlled impedance matching while significantly reducing power consumption by eliminating the high-Q resonant requirements of LC tanks.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS8913978B2RTWO-based down converter

Publication Date: 2014.12.16 ANALOG DEVICES INC

AI summary

A multiphase mixer using a rotary traveling wave oscillator is disclosed. In addition to the oscillator, the mixer includes first and second mixer circuits. The rotary traveling wave oscillator generates a first set of N/2 phase and a second set of N/2 phases, where each phase has a frequency that is a factor of N/2 less than the incoming radio frequency signal. The first set of phases are sine signals and the second set of phases are cosine signals. The first mixer circuit generates a first down-converted signal from the first set of phases and the incoming rf signal. The second mixer circuit generates a second down-converted signal from the second set of phases and the rf signal.