Local Oscillator Phase Cancellation for Jitter and Noise Reduction

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing timing generators and signal sources face challenges in reducing phase noise, period jitter, and spurious deterministic contamination, which affect spectral efficiency and data encoding/decoding accuracy.

Innovation Solution

The technique involves demodulating phase noise and other contamination to baseband, inverting the baseband signal, and using it to modulate the source signal, effectively reducing phase noise and period jitter through phase detection and modulation processes, even in systems with narrow channel spacing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional timing generators are used, then basic signal generation is achieved, but phase noise and period jitter contaminate the signal

Engineering Contradiction:

Improvephase noise reductionVSAvoidphase contamination

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent extracts phase noise and contamination from the signal by demodulating it to baseband, separating the harmful phase components from the clean carrier signal. This extracted baseband noise is then inverted and used to cancel the original contamination in the output signal.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the harmful phase noise and contamination into a useful cancellation signal by demodulating it to baseband, inverting it, and using it to modulate the clean carrier signal. The previously harmful contamination becomes the mechanism for its own cancellation.

Inventive Principle:

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

2Productivity

If signal processing is added to reduce phase noise, then spectral efficiency improves, but device complexity increases

Engineering Contradiction:

Improvespectral usage efficiencyVSAvoidsignal processing complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent segments the signal processing into distinct functional blocks: a demodulator to extract baseband phase noise, an inverter to reverse the contamination, and a modulator to reapplied the inverted noise for cancellation. This segmentation makes the complex processing manageable and implementable.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces baseband signal as an intermediary carrier that transports the phase noise information from the contaminated signal to the cancellation point. This intermediary allows the noise to be processed and inverted before being used to clean the original signal.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If phase cancellation is implemented, then phase noise is reduced, but period jitter and spurious components remain

Engineering Contradiction:

Improvephase noise reductionVSAvoidsignal purity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent makes the phase cancellation mechanism universal by designing it to handle not only phase noise but also period jitter and spurious deterministic contamination. The same demodulate-invert-modulate process addresses multiple types of signal contamination simultaneously.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent implements feedback by continuously monitoring the phase contamination through demodulation, inverting it, and feeding the inverted version back into the signal path through modulation. This closed-loop approach continuously cancels phase noise and other contamination as they appear.

Inventive Principle:

Principle #23Feedback

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 significantly reduces phase noise and spurious components, enabling improved spectral usage efficiency and increased subscriber capacity in wireless systems, such as GSM, by minimizing phase contamination in transmitters and receivers.

Implementation Method 1

phase detection and modulation processes

Methodology Applied

Scientific EffectPhase detection:

Implementation Method 2

using the inverted baseband signal to modulate the source signal

Methodology Applied

Scientific EffectPhase modulation: Phase Modulation

Data Source

PatentUS8750441B2Signal cancellation to reduce phase noise, period jitter, and other contamination in local oscillator, frequency timing, or other timing generators or signal sources

Publication Date: 2014.06.10 TEXAS INSTRUMENTS INC

AI summary

A method includes obtaining an input signal and demodulating phase contamination in the input signal to generate a baseband signal. The method also includes modulating the input signal based on the baseband signal to generate an output signal, where the output signal has less phase contamination than the input signal. The phase contamination could be demodulated using a phase demodulator or a frequency modulation (FM) detector. A portion of the input signal could be down-converted to a lower frequency, and the phase contamination in the down-converted portion of the input signal could be demodulated. Additional phase contamination in the output signal can be demodulated and used to regulate a level of the baseband signal used during modulation of the input signal. The output signal could have less phase noise or period jitter than the input signal.