Sigma-Delta Phase Synthesis With PLL Noise Shaping

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Solution Overview

Problem

Current data encoding methods in time and frequency domains face challenges in effectively filtering noise outside the band of interest, particularly in achieving high signal-to-noise ratios and efficient noise shaping.

Innovation Solution

The implementation of a circuit and method utilizing digital-to-time and digital-to-frequency converters, combined with phase locked loop circuits, for encoding data as time variations and frequency shifts, respectively, to filter noise and enhance signal quality through noise shaping techniques.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If digital-to-time converter encodes data as time variations, then signal-to-noise ratio is improved, but noise outside the band of interest remains

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoidnoise outside band of interest

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

A phase locked loop circuit is introduced as an intermediary component between the digital-to-time converter and the output. The PLL acts as a mediator that filters out noise outside the band of interest while preserving the encoded signal, thus resolving the contradiction between improving signal-to-noise ratio and eliminating out-of-band noise

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If digital-to-frequency converter encodes data as frequency shifts, then data conversion accuracy is improved, but filtering complexity increases

Engineering Contradiction:

Improvedata conversion accuracyVSAvoidfiltering complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex filtering mechanisms with a phase locked loop circuit that naturally performs frequency tracking and filtering. The PLL substitutes for traditional complex filters by using feedback control to lock onto the desired frequency signal and reject out-of-band noise, thereby maintaining data conversion accuracy while reducing filtering complexity

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If noise shaping techniques are applied, then in-band signal quality is enhanced, but out-of-band noise is amplified

Engineering Contradiction:

Improvein-band signal qualityVSAvoidout-of-band noise

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The phase locked loop circuit converts the harmful out-of-band noise amplified by noise shaping into a beneficial filtering opportunity. The PLL's frequency selective properties allow it to pass the in-band signal while attenuating the out-of-band noise, thus converting the harmful effect of noise shaping into a benefit by enabling selective frequency filtering

Inventive Principle:

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

Data Source

PatentUS8855215B2Phase/frequency synthesis using periodic sigma-delta modulated bit-stream techniques

Publication Date: 2014.10.07 MCGILL UNIV

AI summary

A method and a circuit are provided for providing phase or frequency synthesis using sigma-delta modulation bit-stream techniques in which data is encoded utilizing sigma-delta modulation and then digital-to-time conversion (DTC) or digital-to-frequency conversion (DFC). In some embodiments this encoded data stream is further subjected to phase or frequency domain filtering, which in some embodiments is carried out by a higher-order phase-locked loop (PLL).