DAC Linearity Correction Using Integrated Current-Source Measurement

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Solution Overview

Problem

Correcting non-linearity in Digital-to-Analog Converters (DACs) is challenging due to the complexity and inefficiency of traditional methods that require multiple measurement circuits for p-type and n-type current sources, leading to significant errors and increased area and power consumption.

Innovation Solution

An apparatus with a DAC cell using p-type and n-type current sources and a single adjustable strength current source, coupled with measurement logic that monitors and adjusts the current sources to correct non-linearity, reducing the need for multiple measurement circuits and improving linearity by correcting odd and even order harmonics using a dumping algorithm.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional multiple measurement circuits are used to correct non-linearity of p-type and n-type current sources separately, then measurement precision may be maintained, but device complexity and area consumption increase significantly

Engineering Contradiction:

Improvelinearity correction precisionVSAvoidmeasurement circuit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines the measurement and correction of p-type and n-type current sources into a single integrated measurement circuit that simultaneously handles both current sources. This merging approach eliminates the need for separate measurement circuits for each current source type, thereby reducing device complexity and area consumption while maintaining the precision needed to correct non-linearity in the DAC cell.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The measurement circuit is designed with universal functionality to measure and correct non-linearity for both p-type and n-type current sources using a unified approach. This multi-functional circuit can adapt to different current source types without requiring separate dedicated circuits, reducing overall system complexity while preserving measurement precision through a single standardized measurement path.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Manufacturing precision

If traditional multiple measurement circuits are used for each current source, then comprehensive error correction is attempted, but area consumption and power consumption increase

Engineering Contradiction:

Improvenon-linearity correction accuracyVSAvoidcircuit area

Core Design Contradiction:

Manufacturing precisionVSArea of stationary object

Solution Approach 1:

The patent merges multiple separate measurement circuits into a single integrated measurement circuit that serves both p-type and n-type current sources. This consolidation dramatically reduces the circuit area required for non-linearity correction while maintaining comprehensive error correction capability through a unified measurement and adjustment mechanism that handles both current source types efficiently.

Inventive Principle:

Principle #5Merging (Combining)

3Measurement precision

If traditional multiple measurement circuits are used for p-type and n-type current sources, then individual correction is attempted, but power consumption increases

Engineering Contradiction:

Improvecurrent source linearityVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by stationary object

Solution Approach 1:

The patent combines the power-consuming measurement and correction operations for p-type and n-type current sources into a single integrated measurement circuit. This merging eliminates redundant measurement operations and shared common circuitry, thereby reducing overall power consumption while maintaining the precision required for accurate linearity correction of both current source types.

Inventive Principle:

Principle #5Merging (Combining)

4Manufacturing precision

If traditional methods are used with separate measurement circuits, then each current source is corrected individually, but significant errors remain and correction effectiveness is reduced

Engineering Contradiction:

Improvelinearity correction accuracyVSAvoidcorrection effectiveness

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent integrates the measurement and correction of p-type and n-type current sources into a unified system that accounts for the interrelationships between the two current sources. This combined approach enables more effective error correction by considering the coupled nature of the current sources, thereby improving reliability and reducing residual errors compared to separate individual correction methods.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10581442B2Apparatus for correcting linearity of a digital-to-analog converter

Publication Date: 2020.03.03 APPLE INC

AI summary

Described is an apparatus which comprises: a digital-to-analog converter (DAC) having a DAC cell with p-type and n-type current sources and an adjustable strength current source which is operable to correct non-linearity of the DAC cell caused by both the p-type and n-type current sources; and measurement logic, coupled to the DAC, having a reference DAC cell with p-type and n-type current sources, wherein the measurement logic is to monitor an integrated error contributed by both the p-type and n-type current sources of the DAC cell, and wherein the measurement logic is to adjust the strength of the adjustable strength current source according to the integrated error and currents of the p-type and n-type current sources of the reference DAC cell.