Self-Calibrating DAC Circuit Without Periodic Recalibration
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Solution Overview
Problem
Conventional digital to analog converters (DACs) with self-calibration functions require periodic recalibration due to current leakage, leading to increased complexity and cost, limiting their applicability in devices requiring synchronization, such as video display devices.
Innovation Solution
A DAC design incorporating a self-calibration signal generator, constant current generators, and a current to voltage converter, where the number of active current generating elements is adjusted based on a self-calibration signal to maintain accurate output voltage, eliminating the need for a capacitor and allowing for one-time self-calibration at startup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If periodic self-calibration is implemented to maintain accuracy, then conversion accuracy is maintained, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the capacitor component from the self-calibration circuit, removing the source of current leakage that necessitated periodic recalibration. By taking out this problematic element, the system achieves one-time calibration without requiring complex periodic recalibration mechanisms.
Solution Approach 2:
The patent implements preliminary self-calibration during the initialization phase before normal operation begins. This preliminary action establishes accurate reference values that remain valid throughout operation, eliminating the need for subsequent periodic calibration actions and reducing overall system complexity.
2Measurement precision
If periodic self-calibration is implemented, then accuracy is maintained, but loss of time occurs due to repeated calibration cycles
Solution Approach 1:
The patent performs self-calibration once during initialization before normal operation. This preliminary calibration action establishes accurate reference values that remain valid throughout the device's operation, eliminating the need for repeated calibration cycles and associated time losses.
3Measurement precision
If charge pump circuitry is added for self-calibration, then voltage reference accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent removes the capacitor component that caused current leakage, eliminating the need for charge pump circuitry to compensate for calibration drift. This extraction of the problematic element reduces manufacturing complexity and cost while maintaining calibration accuracy through one-time self-calibration.
Solution Approach 2:
The patent employs a simpler self-calibration implementation that uses basic circuit elements rather than expensive charge pump circuitry. The one-time calibration approach uses minimal components, effectively replacing complex expensive calibration hardware with simpler, more cost-effective solutions.
Data Source
AI summary
A digital to analog converter (DAC) converting a digital code to an output voltage and capable of self calibration. The DAC includes a self-calibration signal generator generating a self-calibration signal based on the output voltage, a constant current generator, a first and a second current provider and a current-voltage converter. The current generating elements of the first and second current providers provide proportional currents, and are enabled/disabled according to the self-calibration signal and the digital code, respectively. The constant current is divided into the actual working current generating elements of the first current provider, and an output current is generated by the actual working current generating elements of the second current provider. The output current is converted to the output voltage by the current-voltage converter.