ADC Noise-Shaped Dither After Sampling to Limit Interference

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Solution Overview

Problem

Analog-to-digital converter (ADC) circuits face challenges in balancing during acquisition, leading to potential digital interferences from references or substrates, which are not effectively addressed by existing noise-shaping dither methods applied at the sampling phase.

Innovation Solution

Implementing noise-shaped dither after the sampling phase in ADC circuits using a digital-to-analog converter (DAC) circuit with a capacitor array and a dither control circuit that selectively applies a dither signal to capacitors based on comparator decisions, balancing the circuit to reduce interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If noise-shaped dither is applied at the sampling phase, then non-linearity errors are transformed into noise, but the ADC circuit becomes unbalanced during acquisition, leading to digital interferences from references or substrates

Engineering Contradiction:

Improveconversion accuracyVSAvoiddigital interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The dither signal is applied after sampling rather than during the acquisition phase, allowing the ADC circuit to remain balanced during the critical acquisition period while still introducing dither before the conversion process to transform non-linearity errors into noise

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The dither application is extracted from the sampling phase and separated into a distinct post-sampling stage, allowing independent control of the balancing condition during acquisition and the noise-shaping function during conversion

Inventive Principle:

Principle #2Taking out (Extraction)

2Object-affected harmful factors

If the ADC circuit is balanced during acquisition, then digital interferences are reduced, but non-linearity errors remain unaddressed

Engineering Contradiction:

Improvedigital interferenceVSAvoidconversion accuracy

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

A dither signal is introduced as an intermediary element between the sampling and conversion stages, serving as a mediator that transforms non-linearity errors into noise without disrupting the balanced state of the ADC circuit during acquisition

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10333543B1Analog-to-digital converter with noise-shaped dither

Publication Date: 2019.06.25 ANALOG DEVICES GLOBAL UNLTD

AI summary

Techniques that allow application of noise-shaped dither without applying dither at sampling, resulting in the analog-to-digital converter (ADC) circuit advantageously being balanced during acquisition. Balancing the ADC circuit at acquisition can reduce the risk of sampling digital interferences that can couple in through the references or substrates.