Time-Interleaved ADC Gain Calibration Using Reference Voltage Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Time-interleaved analog-to-digital converters (ADCs) face challenges in maintaining consistent gain across multiple units due to random variations in electrical parameters, leading to gain errors and offset issues, which traditional offset cancellation techniques cannot fully address, especially when external sources contribute to these errors.
Innovation Solution
A digital gain calibration method is introduced, where a digital gain controller adjusts the reference voltage of ADC units by comparing actual outputs to expected outputs, using a predefined analog input signal and a differential reference voltage, to minimize gain errors and offset variations, ensuring accurate digital conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple ADC units are used in time-interleaved configuration to increase sampling rate, then productivity is improved, but gain errors and offset variations worsen due to random variations in electrical parameters
Solution Approach 1:
The patent applies preliminary action by performing gain calibration before normal ADC operation. A calibration phase is executed first where known test signals are input to each ADC unit, and the measured outputs are used to compute correction factors. These correction factors are stored and applied during subsequent normal operation, thereby eliminating gain errors before they affect production conversions and ensuring measurement precision is maintained at high sampling rates
Solution Approach 2:
The patent implements feedback by creating a closed-loop calibration system. The actual output of each ADC unit is compared against the expected output from a reference ADC, and the difference (error signal) is fed back to adjust the gain of each unit. This feedback mechanism continuously compensates for gain variations, allowing the system to maintain measurement precision even when operating at high sampling rates with multiple ADC units
2Measurement precision
If traditional offset cancellation techniques are used, then offset errors are reduced, but gain errors from external sources cannot be addressed
Solution Approach 1:
The patent applies universality by creating a calibration framework that handles multiple types of errors through a single integrated process. The calibration system simultaneously corrects for offset errors, gain errors, and interactions between them by using a comprehensive error model that accounts for both internal ADC variations and external source contributions. This multi-functional approach eliminates the need for separate offset and gain correction circuits, providing versatile error correction capability while maintaining measurement precision
Data Source
AI summary
A time-interleaved analog-to-digital converter (ADC) includes a plurality of ADC blocks each including: at least one ADC unit configured to convert an analog input to a digital output; and a digital gain controller configured to adjust a reference voltage of the at least one ADC unit based on a comparison of an actual output of the at least one ADC unit to an expected output of the at least one ADC unit.