Dual-Path ADC Linearity Correction for VCO Weak-Signal Paths

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Solution Overview

Problem

Conventional dual-path ADC systems face challenges in achieving high dynamic range without introducing noise and power consumption due to the need for amplifiers, which also occupy significant area.

Innovation Solution

Implementing a dual-path ADC system with a closed-loop ADC for strong signals and an open-loop VCO-based ADC for weak signals, utilizing non-linear cancellation to remove non-linearities in the VCO-based ADC output, thereby eliminating the need for pre-amplifiers and reducing noise and power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an amplifier is used in the weak signal path to achieve high dynamic range, then the dynamic range is improved, but noise and power consumption increase

Engineering Contradiction:

Improvedynamic rangeVSAvoidnoise

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent removes the amplifier component from the weak signal path entirely, replacing it with a VCO-based ADC that directly converts weak analog signals to digital signals without requiring amplification, thereby eliminating the noise and power consumption associated with amplifiers

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent substitutes the conventional amplifier-based signal conditioning approach with a VCO-based direct conversion approach, where the voltage-controlled oscillator directly converts the weak analog signal to a digital frequency domain representation, eliminating the need for analog amplification

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If an amplifier is used in the weak signal path to achieve high dynamic range, then the dynamic range is improved, but power consumption increases

Engineering Contradiction:

Improvedynamic rangeVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The amplifier is extracted and removed from the signal path, replacing it with a VCO-based ADC that consumes less power while achieving the same or better dynamic range performance through direct frequency-domain conversion

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The power-hungry analog amplifier is replaced with a more power-efficient VCO-based digital conversion system that achieves high dynamic range through frequency-domain processing rather than analog amplification

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If an amplifier is used in the weak signal path to achieve high dynamic range, then the dynamic range is improved, but the system area increases

Engineering Contradiction:

Improvedynamic rangeVSAvoidsystem area

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The amplifier component is removed from the system architecture, eliminating its physical footprint and replacing it with a compact VCO-based ADC implementation that achieves the same dynamic range in a smaller area

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The bulky analog amplifier circuitry is replaced with a compact VCO-based direct conversion system that achieves high dynamic range performance with reduced physical area requirements

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Object-generated harmful factors

If a VCO-based ADC is used for weak signals, then noise and power consumption are reduced, but non-linearity is introduced

Engineering Contradiction:

ImprovenoiseVSAvoidlinearity

Core Design Contradiction:

Object-generated harmful factorsVSManufacturing precision

Solution Approach 1:

The patent converts the harmful non-linearity introduced by the VCO-based ADC into a measurable and correctable parameter by capturing both the linear and non-linear components through dual-path processing, then using digital signal processing to remove the non-linearity and recover the original linear signal

Inventive Principle:

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

Solution Approach 2:

The patent implements a nested processing structure where the VCO-based ADC output containing non-linearities is processed through a digital filter that extracts and removes the non-linear components, nesting the correction process within the overall signal processing chain

Inventive Principle:

Principle #7Nested doll (Nesting)

Data Source

PatentUS9503112B1Non-linearity cancellation in a dual-path ADC

Publication Date: 2016.11.22 CIRRUS LOGIC INC

AI summary

The overall performance of a dual-path ADC system may be improved by using a VCO-based ADC for small-amplitude signals and employing non-linear cancellation to remove nonlinearities in signals output by the VCO-based ADC. In particular, VCO-based dual-path ADC systems of this disclosure may be configured to receive a first digital signal from a first ADC and a second digital signal from a second ADC, wherein the second digital signal is more non-linear than the first digital signal. The dual-path systems may also be configured to determine one or more non-linear coefficients of the second digital signal based, at least in part, on processing of the first and second digital signals. The dual-path systems may be further configured to modify the second digital signal based, at least in part, on the determined one or more non-linear coefficients to generate a more linear second digital signal.