Interleaved ADC Reference Calibration for Full-Scale Matching
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Solution Overview
Problem
Time-interleaved analog-to-digital converters (ADCs) face challenges in achieving full resolution due to mismatch errors caused by process, voltage, and temperature variations, leading to differences in gain or full scale and DC offsets among individual ADCs, which degrade performance and dynamic range.
Innovation Solution
An integrated circuit with a full-scale reference generation circuit that includes analog and digital components to generate and adjust full-scale reference voltages, using open-loop buffers and digital-to-analog converters to correct for variations, and a calibration circuit to determine and provide feedback for matching the full scales of interleaved ADCs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple ADCs are operated in parallel to increase sampling rate, then productivity is improved, but manufacturing precision deteriorates due to mismatch errors and process variations
Solution Approach 1:
The patent divides the full-scale reference generation into separate segments for each ADC channel. Each ADC receives its own dedicated full-scale reference voltage generated by individual reference generator circuits, allowing independent adjustment and calibration of each channel's full scale to compensate for process variations and mismatch errors.
Solution Approach 2:
The patent changes the full-scale reference voltage parameter for each ADC channel through separate adjustment mechanisms. Digital-to-analog converters (DACs) are used to generate adjustable full-scale reference voltages that can be individually tuned for each ADC, enabling compensation of gain and full-scale variations without affecting other channels.
2Measurement precision
If digital post-processing is used to correct mismatch errors, then measurement precision is improved, but object-generated harmful factors worsen due to noise amplification
Solution Approach 1:
The patent replaces digital post-processing correction with an analog-domain solution. Full-scale reference generator circuits with DACs generate adjusted reference voltages that pre-correct for mismatch errors before the ADC conversion process, eliminating the need for digital multiplication operations that amplify noise.
Solution Approach 2:
The patent introduces full-scale reference generator circuits as intermediary components between the reference voltage source and each ADC. These intermediary circuits include DACs that convert digital correction codes into analog voltage adjustments, providing a smooth transition and avoiding direct digital manipulation that would amplify quantization noise.
3Device complexity
If a common full-scale reference is used for multiple ADCs, then device complexity is reduced, but measurement precision deteriorates due to inability to account for non-reference-related mismatch
Solution Approach 1:
The patent segments the full-scale reference generation into channel-specific components. Each ADC has its own full-scale reference generator circuit that can be independently adjusted, allowing compensation for channel-specific mismatch errors that a common reference cannot address.
Solution Approach 2:
The patent makes the full-scale reference voltages dynamic and adjustable through DACs in each reference generator circuit. This allows the system to adapt to process variations and mismatch errors by programmatically adjusting each channel's full scale, whereas a common reference would be static and unable to compensate for channel-specific variations.
Data Source
AI summary
An integrated circuit may include a full-scale reference generation circuit that corrects for variation in the gain or full scale of a set of interleaved analog-to-digital converters (ADCs). Notably, the full-scale reference generation circuit may provide a given full-scale or reference setting for a given interleaved ADC, where the given full-scale setting corresponds to a predefined or fixed component and a variable component (which may specify a given full-scale correction for a given full scale). For example, the full-scale reference generation circuit may include a full-scale reference generator replica circuit that outputs a fixed current corresponding to the fixed component. Furthermore, the full-scale reference generation circuit may include a full-scale reference generator circuit that outputs a first voltage corresponding to the given full-scale setting based at least in part on the fixed current and a variable current that, at least in part, specifies the given full-scale correction.