Multi-String DAC Leakage Cancellation for Precision Conversion
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Solution Overview
Problem
Leakage current in string digital-to-analog converters (DACs) leads to significant errors, particularly in low power and high temperature applications, as it corrupts the conversion process and is not efficiently addressed by existing technologies.
Innovation Solution
A leakage cancellation circuit is introduced that detects and replicates the leakage current at output nodes, generating a complementary signal to cancel it out through destructive interference, effectively reducing errors in DAC systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If string DAC is used for medium-to-high resolution conversion, then conversion precision is improved, but leakage current error increases
Solution Approach 1:
The patent applies the 'Blessing in disguise' principle by using the leakage current itself as the signal to be converted. The switch network converts the leakage current from the impedance string into a usable current signal that represents the digital input value. This converted leakage current is then subtracted from the main output current, effectively canceling the error while maintaining the benefits of high-resolution conversion.
Solution Approach 2:
The patent extracts the leakage current component from the total output current by using a separate switch network that mirrors the switching pattern. This extracted leakage current is then removed from the main output through subtraction, isolating and eliminating the harmful leakage component while preserving the desired conversion signal.
2Use of energy by moving object
If low power operation is used, then energy consumption is reduced, but leakage current impact increases
Solution Approach 1:
In low power operation, the patent converts the previously harmful leakage current into a useful signal. The switch network captures and converts the leakage current into a representative current signal that is then subtracted from the output. This approach allows the system to maintain high precision while operating at low power levels, as the leakage current that would normally cause errors is now being utilized and eliminated systematically.
3Productivity
If high temperature operation is used, then processing capability is improved, but leakage current increases
Solution Approach 1:
The patent addresses high temperature leakage by converting the temperature-dependent leakage current into a useful signal. The switch network captures the leakage current and converts it into a proportional current signal that reflects the digital input value. This converted signal is then subtracted from the main output, effectively canceling the temperature-induced leakage errors while maintaining processing capability.
Solution Approach 2:
The patent implements a feedback mechanism where the leakage current is continuously monitored and converted by the switch network. The converted leakage signal is fed back to the output node for cancellation, creating a closed-loop system that automatically compensates for temperature-dependent leakage variations without requiring external temperature sensing or adjustment.
4Measurement precision
If leakage current cancellation circuit is added, then conversion accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the leakage cancellation function with the existing DAC switch network. The same switches that control the main output also control the leakage current conversion path. By combining these functions into a single integrated switch network, the patent achieves leakage cancellation without adding separate complex cancellation circuitry, thus minimizing the increase in device complexity.
Solution Approach 2:
The switch network in the patent serves multiple functions simultaneously: it controls the main output current selection, converts the leakage current into a usable signal, and enables the leakage cancellation process. This multi-functionality eliminates the need for dedicated leakage cancellation components, reducing overall circuit complexity while maintaining high conversion accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution significantly reduces leakage current-induced errors in DAC systems, improving accuracy and reliability across various applications, especially in low power and high temperature conditions.
Implementation Method 1
generating a complementary signal of the leakage current and to output the complementary signal to the output node
Data Source
AI summary
Embodiments of the present invention may provide a multi-string DAC with leakage current cancellation. A leakage cancellation circuit may be coupled to output node(s) of the—multi-string DAC. The leakage cancellation circuit may replicate leakage current present at the coupled output node(s) and generate a corresponding complementary signal, a leakage cancellation signal. The leakage cancellation signal may be injected into the coupled output node(s) to cancel (or reduce) the net impact of the leakage current.