SAR ADC Digital Calibration for Capacitor Mismatch Precision
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Solution Overview
Problem
Existing ADC calibration systems require multiple physical perturbation capacitors, increasing design costs and space, and have limited precision due to applying perturbation values in the analog domain, which is inefficient for calibrating successive approximation register (SAR) ADCs.
Innovation Solution
An all-digital domain calibration architecture that applies perturbation values in the digital domain to test and calibrate SAR ADCs, reducing hardware requirements and enhancing precision by using digital perturbation values to correct capacitor mismatch and other accuracy issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple physical perturbation capacitors are used for ADC calibration, then calibration capability is provided, but hardware cost and space increase
Solution Approach 1:
The patent replaces physical perturbation capacitors (analog domain components) with digital perturbation values applied in the digital domain. Instead of using multiple physical capacitors to introduce perturbations, the invention uses digital code modifications that are processed through the existing DAC and ADC architecture, thereby eliminating the need for additional physical calibration components while maintaining calibration functionality.
Solution Approach 2:
The patent creates a digital model of the calibration process where digital perturbation values represent the effect of physical capacitors. By working with digital representations of perturbation rather than physical capacitor variations, the system achieves calibration capability without requiring physical copies of perturbation components.
2Reliability
If perturbation values are applied in the analog domain, then calibration is performed, but precision is limited
Solution Approach 1:
The patent substitutes analog domain perturbation application with digital domain perturbation application. By introducing perturbation values in the digital domain before DAC conversion, the system leverages the higher precision of digital signal processing while maintaining the same calibration function that would otherwise require analog perturbation signals with limited precision.
3Reliability
If multiple physical perturbation capacitors are used, then calibration is enabled, but manufacturing cost increases
Solution Approach 1:
The patent eliminates the need to manufacture and assemble multiple physical perturbation capacitors by implementing calibration through digital signal processing. This substitution of physical components with digital algorithms significantly reduces manufacturing complexity and cost, as no additional analog components need to be fabricated, tested, or assembled into the ADC device.
Data Source
AI summary
A method is described that is performed by a calibration system. The method includes determining a set of perturbation values for configuring an analog-to-digital converter of the calibration system; generating a set of digital test values for determining the accuracy of the analog-to-digital converter; and applying the set of perturbation values to the set of digital test values to generate a set of modified test values, wherein the set of perturbation values are digital values that are applied to the set of digital test values in the digital domain.