Current-Mirror DAC for Stable Setpoint Voltage Generation
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Solution Overview
Problem
Conventional setpoint reference voltage generators suffer from low accuracy over temperature and lifetime due to device drift and mismatch of integrated circuit components, which affects the regulation of output voltage in power converters.
Innovation Solution
The implementation of a digital-to-analog converter with a sequence of current drive modules that switch between modes to produce and mirror reference currents, using dynamic element matching to improve linearity and reduce gain and offset drift, including a controller to adjust current drive module operations based on error signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional setpoint reference voltage generators are used, then the circuit structure is simple, but the setpoint accuracy drifts over temperature and lifetime due to device mismatch
Solution Approach 1:
The DAC is divided into multiple current drive modules, each with identical segmented circuit structures. This segmentation allows for better matching between corresponding components in each module while maintaining overall system functionality. The segmented design enables independent optimization of each module to reduce drift.
Solution Approach 2:
Multiple current drive modules are created as identical copies of each other, with each module containing mirrored circuit structures. This copying approach ensures that corresponding components across modules have matched characteristics, reducing differential drift. The modules can be selectively activated based on temperature and lifetime conditions.
2Reliability
If device matching techniques are used to reduce drift, then setpoint accuracy improves, but the device complexity and calibration requirements increase
Solution Approach 1:
The system performs self-calibration by automatically adjusting the operation of individual current drive modules based on feedback from the output voltage. The controller monitors voltage deviations and dynamically reconfigures which modules are active, eliminating the need for external manual calibration while maintaining high accuracy over temperature and lifetime variations.
Solution Approach 2:
A feedback mechanism continuously monitors the output voltage and compares it against the desired setpoint. Based on this feedback, the controller adjusts the configuration of current drive modules in real-time, compensating for drift without requiring external intervention. This closed-loop approach maintains reliability while simplifying the calibration process.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
Digital-to-analog converter circuitry comprising a sequence of multiple current drive modules. The sequence may include a first current drive module and a second current drive module of a digital-to-analog converter. The first current drive module is switchable between: i) a first mode of producing a first reference current that is mirrored by a second current drive module coupled to the first current drive module; and ii) a second mode of mirroring a second reference current that is produced by the second current drive module or a third current drive module coupled to the first current drive module.