ADC Supply-Rail References for Low-Noise High-Resolution Conversion

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing analog-to-digital converters (ADCs) face challenges with noise, power consumption, and area occupancy due to large capacitors and reference voltage buffering, which affect conversion speed and resolution, especially when dealing with small reference voltages and multiple units in interleaved arrays.

Innovation Solution

The use of power-supply voltages as reference voltages to define a full-scale range for ADCs, allowing for increased bit resolution and error correction without the need for buffer circuits and large capacitors, by scaling the quantized output based on the ratio of power-supply voltages to reference voltages, and incorporating interleaved unit ADCs for correction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If large bypass capacitors are used to stabilize reference voltages and reduce noise, then noise is reduced and stability is improved, but area occupancy increases and device complexity increases

Engineering Contradiction:

Improvereference voltage stabilityVSAvoidcapacitor area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent extracts the reference voltage function from dedicated reference voltage generating circuits and uses the power supply voltages themselves as reference voltages. This eliminates the need for separate reference voltage buffers and large bypass capacitors, thereby reducing area occupancy while maintaining voltage stability for ADC operation

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The power supply voltages are made to serve dual functions: both as power sources and as reference voltages for the ADC. This multi-functionality eliminates the need for separate reference voltage circuits and their associated large capacitors, reducing overall circuit area while maintaining stability

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Object-affected harmful factors

If reference voltage buffering circuits are used to reduce noise, then noise is reduced, but power consumption increases

Engineering Contradiction:

ImprovenoiseVSAvoidpower consumption

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The patent removes the reference voltage buffering circuitry from the system by directly using power supply voltages as references. This extraction eliminates the power-consuming buffer operations while maintaining low noise through proper power supply design and interleaved ADC architecture

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The power supply voltages serve themselves as reference voltages without requiring external buffering or stabilization circuits. The power supply network inherently provides the reference function, eliminating the need for additional power-consuming active components

Inventive Principle:

Principle #25Self-service

3Measurement precision

If the number of bits of quantization is increased to maintain resolution, then resolution is maintained, but conversion speed decreases

Engineering Contradiction:

Improveconversion resolutionVSAvoidconversion speed

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The patent divides the ADC system into multiple interleaved unit ADCs that operate in parallel. Each unit ADC processes a portion of the input signal spectrum, allowing higher effective resolution without increasing the conversion time of individual units, thereby maintaining both resolution and conversion speed

Inventive Principle:

Principle #1Segmentation

4Measurement precision

If smaller reference voltages are used to detect small-amplitude input signals, then sensitivity is improved, but switch resistance increases

Engineering Contradiction:

Improvesignal detection sensitivityVSAvoidswitch resistance

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the operating parameters of the feedback switches by using power supply voltages with sufficient overdrive voltage to maintain low resistance. This allows the use of smaller effective reference voltages for improved sensitivity while keeping switch resistance low through optimized power supply voltage selection and switch sizing

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11632122B2Stable low-power analog-to-digital converter (ADC) reference voltage

Publication Date: 2023.04.18 AYDEEKAY LLC

AI summary

A conversion circuit that performs analog-to-digital conversion is described. During operation, the conversion circuit receives an input signal. Then, the conversion circuit performs analog-to-digital conversion and provides a quantized output corresponding to the input signal based at least in part on a first power-supply voltage and a second power-supply voltage of the conversion circuit. For example, the quantized output may be based at least in part on a comparison of the input signal to the first power-supply voltage and the second power-supply voltage. Moreover, the first power-supply voltage and the second power-supply voltage may specify a full-scale range of the conversion circuit. When the full-scale range exceeds a second full-scale range associated with reference voltages that are other than the first power-supply voltage and the second power-supply voltage, the quantized output may correspond to a larger number of bits than when the full-scale range equals the second full-scale range.