Injection-Locked Ring Oscillator for Low-Noise Multi-Phase Output

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Solution Overview

Problem

Conventional methods for generating multiple phases using low-noise oscillators are costly in terms of surface area and power consumption, and ring oscillators suffer from noise, inaccuracy, and temperature drift.

Innovation Solution

A multiple phase oscillator system comprising a master oscillator injection locked to a ring oscillator, with a secondary ring oscillator and a control loop to adjust the free-running frequency and power consumption, incorporating a temperature compensation circuit to maintain stability over a wide temperature range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple low-noise oscillators are coupled together to provide more phases, then the number of phases is increased, but the surface area and power consumption increase significantly

Engineering Contradiction:

Improvenumber of phasesVSAvoidsurface area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent combines a low-noise master oscillator with a ring oscillator that is injection-locked to it. The ring oscillator generates multiple phases (e.g., four phases in quadrature) while being frequency-controlled by the master oscillator, thereby achieving multi-phase output without requiring multiple separate low-noise oscillators, thus reducing surface area

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The ring oscillator serves multiple functions: it generates multiple phase outputs, is frequency-controlled by the master oscillator for accuracy, and its free-running frequency can be adjusted via control signal for adaptability. This single component replaces what would otherwise require multiple dedicated oscillators

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If multiple low-noise oscillators are coupled together to provide more phases, then the number of phases is increased, but the power consumption increases significantly

Engineering Contradiction:

Improvenumber of phasesVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by stationary object

Solution Approach 1:

The patent merges the frequency control function of the master oscillator with the multi-phase generation function of the ring oscillator. The ring oscillator consumes less power than multiple low-noise oscillators while still providing accurate frequency control through injection locking, thereby reducing overall power consumption

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The control loop periodically adjusts the control signal to the ring oscillator's current source to maintain the desired free-running frequency. This periodic adjustment ensures frequency accuracy while allowing the ring oscillator to operate at optimal power levels

Inventive Principle:

Principle #19Periodic action

3Device complexity

If ring oscillators are used for multiple phase generation, then the device complexity is reduced, but noise and temperature drift increase

Engineering Contradiction:

Improvedevice complexityVSAvoidnoise and temperature stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent implements a control loop that monitors the ring oscillator's output frequency and adjusts its control signal accordingly. This feedback mechanism compensates for temperature drift and maintains frequency accuracy, thereby improving reliability without significantly increasing device complexity

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The master oscillator acts as an intermediary that provides a stable reference frequency to the ring oscillator through injection locking. This intermediary connection allows the ring oscillator to benefit from the master oscillator's frequency stability and low noise characteristics while maintaining its simpler structure

Inventive Principle:

Principle #24Intermediary (Mediator)

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

The system achieves low-noise, accurate multiple phases with reduced power and surface area consumption, while maintaining stability and accuracy across varying temperatures with minimal power usage.

Implementation Method 1

a master oscillator; a main ring oscillator connected to be injection locked to the low-noise oscillator

Methodology Applied

Scientific EffectInjection locking:

Implementation Method 2

The control loop may comprise a frequency-to-voltage converter connected to an output of the secondary ring oscillator

Methodology Applied

Scientific EffectFrequency-to-voltage conversion:

Implementation Method 3

The constant reference voltage and the conversion factor of the frequency-to-voltage converter may be based on band-gap references

Methodology Applied

Scientific EffectBand-gap reference:

Data Source

PatentUS9419634B1Low-noise multiple phase oscillator

Publication Date: 2016.08.16 STMICROELECTRONICS INT NV

AI summary

A multiple phase oscillator includes a master oscillator that injection locks a first ring oscillator. The free-running frequency of the first ring oscillator is adjustable through a control signal. A second ring oscillator has a same structure as the first ring oscillator and is connected to operate in a free-running mode. The free-running frequency of the second ring oscillator is adjustable through the control signal. A control loop senses the output of the second ring oscillator and adjusts the control signal so that the free-running frequency of the second ring oscillator matches a desired value.