Single-ADC Difference Conversion for Higher-Resolution Sensing
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Solution Overview
Problem
Existing A/D converters face challenges in achieving high accuracy with a single A/D conversion circuit, as most high-accuracy implementations require two A/D conversion circuits, such as Coarse and Fine ADCs, which introduce errors and complexity.
Innovation Solution
The proposed A/D converter configuration includes a D/A conversion circuit, a difference output circuit, and an A/D conversion circuit, where the control circuit outputs two different DAC input digital values to perform A/D conversions, allowing the A/D converter to achieve higher accuracy by performing conversions based on the difference between the input signal and DAC output signals, thereby increasing resolution without the need for two separate A/D conversion circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two A/D conversion circuits (Coarse ADC and Fine ADC) are used to achieve high accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the A/D conversion process into multiple stages with different DAC input digital values, where each stage processes a portion of the conversion task. Instead of using multiple parallel A/D conversion circuits, the single circuit performs sequential conversions with varying DAC inputs, dividing the high-accuracy conversion task into manageable segments that reduce overall system complexity while maintaining precision.
Solution Approach 2:
The patent employs periodic action by repeatedly performing A/D conversion operations with different DAC input digital values (first, second, third values). The control circuit systematically varies the DAC input across multiple conversion cycles, allowing the single A/D conversion circuit to accumulate precision through repeated measurements with different reference levels, effectively replacing the need for multiple simultaneous circuits.
2Measurement precision
If multiple A/D conversion circuits are used to improve accuracy, then measurement precision is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent merges the functions of multiple A/D conversion circuits into a single circuit by combining the reference DAC functionality with the conversion process. Instead of requiring precise matching between separate Coarse ADC and Fine ADC circuits, the invention uses one unified A/D conversion circuit that references its own DAC output, eliminating inter-circuit matching errors and reducing manufacturing precision requirements.
Solution Approach 2:
The patent implements feedback by using the DAC output signal as a reference for the A/D conversion process. The control circuit adjusts DAC input digital values based on previous conversion results, creating a feedback loop that continuously refines the measurement. This self-referencing approach reduces sensitivity to manufacturing variations compared to systems requiring precise matching between independent circuits.
3Device complexity
If a single A/D conversion circuit is used to simplify design, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent adds a temporal dimension to the single A/D conversion circuit by performing multiple conversion operations with different DAC input values over time. Instead of relying on spatial multiplication (multiple parallel circuits), the invention uses time-multiplexed conversions with varying reference levels, effectively increasing measurement precision through dimensional expansion of the conversion process rather than through circuit multiplication.
Solution Approach 2:
The patent changes the DAC input digital value parameter across multiple conversion operations. By systematically varying this parameter (first value, second value, third value) and using the results to calculate the final high-precision output, the single A/D conversion circuit achieves accuracy comparable to multiple circuits. The precision improvement comes from parameter variation and mathematical synthesis rather than from additional hardware.
Data Source
AI summary
The A/D converter includes a D/A conversion circuit configured to perform a D/A conversion on a DAC input digital value to output a DAC output signal, a difference output circuit for outputting difference signals based on a difference between the input signal and the DAC output signal, an A/D conversion circuit for performing an A/D conversion on the difference signals to output an ADC output digital value, and a control circuit for outputting the DAC input digital value based on the ADC output digital value. The control circuit outputs a first DAC input digital value and a second DAC input digital value different from the first DAC input digital value, and obtains ADC result data based on a first ADC output digital value obtained in accordance with the first DAC input digital value, a second ADC output digital value obtained in accordance with the second DAC input digital value, and the DAC input digital value.