Hybrid ADC Reference Circuit With Filtered Stage Isolation

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Solution Overview

Problem

Hybrid analog-to-digital converters (ADCs) face interference issues between stages, degrading performance due to shared reference signals, which requires accurate and independent reference signals for each stage to maintain optimal operation.

Innovation Solution

A circuit and method utilizing different reference sources integrated on the same circuit to provide distinct reference signals to each stage of the hybrid ADC, with a low-pass filter to eliminate interference and allow independent bandwidth design, reducing the need for external supplies and calibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a shared reference signal is used for multiple stages of hybrid ADC, then device complexity is reduced, but interference between stages occurs and measurement precision deteriorates

Engineering Contradiction:

Improvereference signal generation complexityVSAvoidreference signal accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent divides the reference signal generation into separate segments for each ADC stage. Each stage has its own reference source (first reference source for first stage, second reference source for second stage), eliminating interference between stages while maintaining manageable complexity through modular design

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by providing different reference signal characteristics to different stages. The first reference signal is optimized for the first ADC stage while the second reference signal is optimized for the second stage, with each having appropriate filtering and bandwidth characteristics suited to its specific stage requirements

Inventive Principle:

Principle #3Local quality

2Measurement precision

If independent reference sources are used for each stage of hybrid ADC, then interference between stages is reduced and measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improvereference signal accuracyVSAvoidreference signal generation complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The reference signal generation is segmented into independent modules: first reference source with first filter for first stage, and second reference source with second filter for second stage. This segmentation provides measurement precision through independence while controlling complexity through modular, reusable design patterns

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs universal design elements such as multiple filters of the same type (low-pass filters) that can be applied to different reference signals. The filter design and reference source architecture can be replicated across stages, reducing overall complexity through standardized multi-functional components

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If filtering is applied to reference signals in hybrid ADC, then interference is reduced and measurement precision is improved, but use of energy increases

Engineering Contradiction:

Improvereference signal qualityVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent optimizes filter parameters (cutoff frequencies, order) to achieve the necessary interference rejection with minimal power consumption. By carefully selecting filter parameters that provide just enough filtering to eliminate interference, the system achieves measurement precision while minimizing the energy use of the filtering operation

Inventive Principle:

Principle #35Parameter changes

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 solution effectively reduces interference between stages, allowing for low-power and low-area operation while ensuring accurate reference signals for both stages of the hybrid ADC, enhancing overall performance.

Implementation Method 1

a low-pass filter coupled to an output of the first reference driver. The low-pass filter may be configured to filter the first reference signal to produce a filtered first reference signal

Methodology Applied

Scientific EffectLow-pass filtering: Filter (electronic)

Data Source

PatentUS10505562B2Circuit and method for generating reference signals for hybrid analog-to-digital convertors

Publication Date: 2019.12.10 STMICROELECTRONICS INT NV

AI summary

An embodiment circuit includes a first reference source configured to provide a first reference signal to an analog-to-digital convertor (ADC). The circuit also includes a filter coupled to an output of the first reference source and configured to filter the first reference signal to produce a filtered first reference signal. The circuit further includes a second reference source coupled to an output of the filter. The second reference source is configured to provide a second reference signal to the ADC, and the second reference signal is generated based on the filtered first reference signal.