ADC Trim Code Selection for Improved Linearity

Solution Overview

Problem

Analog-to-digital converters face challenges in achieving linearity due to component mismatches, particularly in switched-capacitor and switched-current designs, where traditional brute-force trimming methods are impractical for high-resolution systems due to the vast number of permutations required for optimal trim code determination.

Innovation Solution

A method that evaluates integral non-linearity responses to identify significant departures, determines trimming factors, and calculates a minimization factor as a sum of weighted residual gap magnitudes to improve linearity without iterative trim-and-measure operations, allowing for one-pass optimization of the ADC's performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If brute-force trimming methods are used to optimize ADC linearity, then manufacturing precision is improved, but time consumption and device complexity increase significantly

Engineering Contradiction:

ImprovelinearityVSAvoidtime consumption

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent pre-calculates and stores optimal trim codes in lookup tables before the ADC operation. During actual conversion, the system simply retrieves the pre-determined trim code based on measured component values, avoiding time-consuming iterative optimization during runtime. This preliminary preparation resolves the contradiction by shifting computational effort from operational time to manufacturing/setup phase.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent divides the trimming optimization problem into independent stages or components, allowing separate optimization of each segment. By breaking down the complex global optimization into manageable local optimizations, the system achieves good linearity without requiring exhaustive search of all possible trim code combinations, thereby reducing time consumption while maintaining manufacturing precision.

Inventive Principle:

Principle #1Segmentation

2Manufacturing precision

If brute-force trimming methods are used to optimize ADC linearity, then manufacturing precision is improved, but device complexity increases

Engineering Contradiction:

ImprovelinearityVSAvoiddevice complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent pre-calculates and stores optimal trim codes in lookup tables before the ADC operation. During actual conversion, the system simply retrieves the pre-determined trim code based on measured component values, avoiding time-consuming iterative optimization during runtime. This preliminary preparation resolves the contradiction by shifting computational effort from operational time to manufacturing/setup phase.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses lookup tables that store pre-computed optimal trim codes, effectively creating a simplified model or copy of the complex optimization problem. Instead of implementing the full brute-force optimization algorithm in hardware, the system stores the results of exhaustive searches in accessible memory structures, reducing hardware complexity while maintaining optimization effectiveness.

Inventive Principle:

Principle #26Copying

3Measurement precision

If iterative trim-and-measure operations are used, then measurement precision is improved, but productivity decreases

Engineering Contradiction:

Improvelinearity measurementVSAvoidoptimization speed

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent pre-calculates and stores optimal trim codes in lookup tables before the ADC operation. During actual conversion, the system simply retrieves the pre-determined trim code based on measured component values, avoiding time-consuming iterative optimization during runtime. This preliminary preparation resolves the contradiction by shifting computational effort from operational time to manufacturing/setup phase.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses the measured component values themselves to directly index into lookup tables and retrieve optimal trim codes, making the optimization process self-sufficient and eliminating the need for external iterative control. The measured data directly serves the optimization function, improving productivity while maintaining precision through the accuracy of the measurement-to-trim-code mapping.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS7411532B2Method for determining minimization factor for improving linearity of an analog-to-digital converter

Publication Date: 2008.08.12 TEXAS INSTRUMENTS INC

AI summary

A method for determining a minimization factor for improving linearity of an analog-to-digital converter including a plurality of components includes the steps of: (a) Evaluating integral non-linearity response of the apparatus to identify significant departures of the response greater than a predetermined amplitude and to relate each respective significant departure with a respective identified component. (b) Determining magnitude of each significant departure. (c) Identifying a trimming factor related with each component. (d) Determining a residual gap magnitude for each significant departure. The residual gap magnitude comprises the magnitude of the respective significant departure less the trimming factor related with the identified component. (e) Determining the minimization factor as a sum of the residual gap magnitudes for a selected plurality of the identified components.