Self-Calibrated Current-Steering DAC for Reduced Glitch Mapping
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Solution Overview
Problem
Existing digital-to-analog converters (DACs) face challenges in achieving accurate and linear output due to the mismatch of current sources, which affects their calibration process and leads to glitches during operation.
Innovation Solution
A self-calibrated DAC design that includes a plurality of current-steering elements, where each element operates under different control signals during calibration and active operation, utilizing a reference generator to ensure accurate matching of source and sink currents, and a rotating calibration scheme to avoid the limitations of traditional calibration architectures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration architectures are used, then current sources can be calibrated, but timing limitations and glitches occur during calibration
Solution Approach 1:
The patent implements dynamic calibration by rotating which current source is calibrated at each time step, allowing the calibration process to adapt continuously without fixed timing constraints. The calibration target changes dynamically based on a rotating index, enabling the system to overcome static timing limitations.
Solution Approach 2:
The calibration process operates continuously during DAC operation rather than requiring separate calibration phases. By integrating calibration into the normal operation timeline and rotating through different current sources, the system maintains continuous useful action without interrupting overall functionality.
2Measurement precision
If current sources are continuously calibrated, then accuracy improves, but glitching increases during calibration
Solution Approach 1:
The patent extracts the calibration function into a separate, dedicated calibration circuit that operates independently from the main DAC output path. By taking out the calibration current sources and their control logic, the calibration process can occur without injecting glitches into the primary signal path.
Solution Approach 2:
The patent introduces intermediary calibration control signals that mediate between the calibration process and the current sources. These intermediary signals coordinate the calibration timing and current routing to minimize direct interference and glitching in the main output path.
3Productivity
If more current-steering elements are calibrated simultaneously, then calibration speed increases, but control complexity increases
Solution Approach 1:
The patent segments the calibration process into discrete time steps, with each step dedicated to calibrating a single current source. This segmentation simplifies control logic at each moment while achieving comprehensive calibration over time, avoiding the complexity of simultaneous multi-source calibration.
Solution Approach 2:
The calibration follows a periodic rotating pattern where each current source is calibrated in sequence at regular intervals. This periodic approach maintains manageable control complexity by repeating a simple calibration routine for each source rather than implementing complex simultaneous calibration control.
Data Source
AI summary
A digital-to-analog converter (DAC) is disclosed. According to some embodiments of the present disclosure, a DAC may include a plurality of current-steering elements, wherein each respective current-steering element is configured to operate as instructed by a respective calibration signal during respective steps in a calibration cycle, and at least one current-steering element is configured to operate as instructed by a first control signal during at least a first step in which the at least one current-steering element is not being calibrated, and operate as instructed by a second control signal during at least a second step in which the at least one current-steering element is not being calibrated.