Multi-Stage ADC Calibration Using an On-Chip Microprocessor
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Solution Overview
Problem
Existing analog-to-digital converters (ADCs) face performance challenges due to errors and artifacts resulting from fabrication limitations and environmental changes, which affect their speed and resolution, and conventional calibration methods are inflexible and require significant design complexity.
Innovation Solution
Incorporating an on-chip microprocessor (uP) with ADCs to perform digital functions for error correction and calibration, enabling flexible and adaptable operation across various applications without the need for fixed, specialized circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional calibration methods are used for ADCs, then manufacturing precision can be improved, but device complexity increases significantly
Solution Approach 1:
The patent implements a universal calibration architecture that can calibrate multiple ADC channels (including time-interleaved channels) using a single shared calibration circuit. The calibration circuit generates calibration codes that are applied to all channels, eliminating the need for separate calibration circuits for each channel and significantly reducing overall device complexity while maintaining calibration precision across all channels.
Solution Approach 2:
The calibration system performs self-calibration by automatically generating calibration codes, measuring errors through the ADC channels, and adjusting calibration parameters without requiring external intervention. The on-chip microprocessor autonomously executes calibration algorithms, eliminating the need for complex external calibration equipment and reducing device complexity.
2Measurement precision
If fixed specialized circuitry is used for error correction, then measurement precision is improved, but adaptability decreases
Solution Approach 1:
The patent replaces fixed specialized circuitry with dynamic, software-controlled calibration logic implemented in an on-chip microprocessor. The microprocessor can adaptively adjust calibration parameters based on measured errors and operating conditions, allowing the same hardware to be reconfigured for different calibration scenarios and ADC channels, thereby maintaining measurement precision while significantly improving adaptability.
Solution Approach 2:
The calibration system dynamically changes calibration parameters (such as calibration codes and correction values) based on measured errors and operating conditions. The microprocessor adjusts these parameters in real-time to optimize ADC performance across different channels and operating scenarios, providing both high measurement precision and adaptability without requiring fixed specialized circuitry for each case.
3Measurement precision
If multiple specialized calibration circuits are implemented for each ADC channel, then measurement precision is maintained, but ease of manufacture decreases
Solution Approach 1:
The patent merges the calibration functionality for multiple ADC channels into a single shared calibration circuit. This calibration circuit generates calibration codes that are distributed to all channels, and a single set of calibration measurements is performed across all channels. This merging approach maintains calibration accuracy for each channel while significantly simplifying the manufacturing process and reducing design complexity compared to implementing separate calibration circuits for each channel.
Solution Approach 2:
The shared calibration circuit is designed to universally calibrate all ADC channels through a unified calibration process. The circuit generates calibration codes and performs measurements that apply to all channels simultaneously, eliminating the need for multiple specialized circuits and making the manufacturing process more straightforward while maintaining the measurement precision required for each individual channel.
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AI summary
Analog-to-digital converters (ADCs) can have errors which can affect their performance. To improve the performance, many techniques have been used to compensate or correct for the errors. When the ADCs are being implemented with sub-micron technology, ADCs can be readily and easily equipped with an on-chip microprocessor for performing a variety of digital functions. The on-chip microprocessor and any suitable digital circuitry can implement functions for reducing those errors, enabling certain undesirable artifacts to be reduced, and providing a flexible platform for a highly configurable ADC. The on-chip microprocessor is particularly useful for a randomized time-interleaved ADC. Moreover, a randomly sampling ADC can be added in parallel to a main ADC for calibration purposes. Furthermore, the overall system can include an efficient implementation for correcting errors in an ADC.