ADC Comparator Calibration for Continuous Conversion Accuracy
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Solution Overview
Problem
Analog-to-digital converters (ADCs) face calibration drift due to temperature and voltage variations, leading to inaccurate conversions over time.
Innovation Solution
Implementing an additional comparator in the ADC system that allows for continuous operation while one comparator is calibrated, using a state machine to manage the calibration process and switches to adjust reference voltages, ensuring all comparators are calibrated without disrupting the conversion process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration is performed at power-on using a DAC, then the comparator's output voltage offset is compensated, but temperature and voltage variations cause the threshold voltage to change and the offset to drift over time, resulting in inaccurate calibration
Solution Approach 1:
The patent performs preliminary calibration actions by storing calibration data in a lookup table during manufacturing or initial setup. This pre-computed calibration data compensates for threshold voltage variations across different operating conditions, eliminating the need for real-time calibration computations while maintaining accuracy throughout the device's operational lifetime.
Solution Approach 2:
The patent replaces the traditional continuous calibration mechanism with a discrete lookup table approach. Instead of dynamically adjusting calibration parameters based on temperature and voltage sensors, the system substitutes this complex feedback mechanism with pre-stored calibration values that can be quickly retrieved based on operating conditions, simplifying the calibration system while maintaining effectiveness.
2Productivity
If an additional comparator is added to enable continuous operation during calibration, then calibration can be performed without disrupting conversion, but the device complexity increases
Solution Approach 1:
The patent segments the comparator functionality by dividing comparators into calibration-mode and conversion-mode units. The additional comparator is dedicated solely to calibration operations, allowing it to be calibrated without affecting the conversion process. This segmentation enables independent optimization of each comparator's function and allows calibration to proceed in parallel with normal conversion operations using other comparators.
Solution Approach 2:
The patent implements multi-functionality by designing the additional comparator to serve dual purposes: it participates in normal conversion operations during standard mode, and is dedicated to calibration operations when needed. This universal design allows the comparator to contribute to both conversion productivity and calibration accuracy without requiring separate dedicated hardware for each function.
Data Source
AI summary
An analog-to-digital converter (ADC) including a plurality of comparators connected to the ADC. The ADC further includes a first pair of terminals and a second pair of terminals connected to each of the plurality of comparators. The ADC further includes a first pair of switches coupled to each of the first pair of terminals and a second pair of switches coupled to each of the second pair of terminals, where the first and second pair of switches are configured to alternate a corresponding comparator between normal operation and a calibration configuration. Comparators other than the corresponding comparator are configured for normal operation if the corresponding comparator is configured to be calibrated.