A/D Converter Calibration Using Dual Reference Comparisons
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Solution Overview
Problem
Existing A/D conversion devices require multiple circuits for continuous calibration, leading to increased power consumption and circuit area.
Innovation Solution
An A/D conversion device that uses a sample-and-hold unit, a single A/D conversion unit, and a digital processing unit to perform conversions twice with different reference voltages, averaging errors to reduce conversion errors and calibrate continuously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple A/D conversion circuits are used for continuous calibration, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent applies periodic action by performing calibration operations at specific intervals during normal A/D conversion. The A/D conversion unit alternates between calibration mode (comparing with reference voltage) and normal conversion mode, allowing continuous calibration without requiring multiple parallel circuits. This periodic switching enables single-circuit calibration while maintaining measurement precision.
Solution Approach 2:
The patent implements continuity of useful action by ensuring calibration occurs continuously during normal operation rather than requiring separate calibration phases. The A/D conversion unit performs both calibration and normal conversion functions sequentially, maintaining ongoing correction of conversion characteristics without interrupting the useful A/D conversion operation.
2Measurement precision
If multiple A/D conversion circuits are used for simultaneous calibration and conversion, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent merges the calibration function and normal A/D conversion function into a single A/D conversion unit. By combining these previously separate functions into one unit that switches between modes, the patent eliminates the need for parallel circuit operation, thereby reducing power consumption while maintaining continuous calibration capability.
Solution Approach 2:
The A/D conversion unit is designed with multi-functionality, serving both as a calibration device and as a normal A/D converter. This universal unit performs reference voltage comparison during calibration periods and analog-to-digital conversion during normal operation, eliminating the need for dedicated separate circuits and reducing overall power consumption.
3Measurement precision
If multiple A/D conversion circuits are used for continuous calibration, then measurement precision is improved, but circuit area increases
Solution Approach 1:
By using periodic action, the patent allows a single A/D conversion unit to perform calibration at intervals during normal operation. This eliminates the need for parallel redundant circuits that would occupy additional chip area, as the same physical circuit is reused alternately for calibration and normal conversion functions.
Solution Approach 2:
The patent merges calibration circuitry and normal conversion circuitry into a single integrated A/D conversion unit. This consolidation reduces the total circuit area required compared to having separate parallel circuits for calibration and conversion, as the same hardware resources are shared between both functions through time-division multiplexing.
Data Source
AI summary
An A/D conversion unit performs an A/D conversion operation twice during a hold period of an analog value. In a first conversion operation, the A/D conversion unit compares the analog value with a first reference voltage and outputs a comparison result as first converted data. In a second conversion operation, the A/D conversion unit compares the analog value with a second reference voltage and outputs a comparison result as second converted data. The second reference voltage is a voltage obtained by adding or subtracting a minimum resolution voltage to or from the first reference voltage. A digital processing unit averages errors of the first and second converted data by digital processing to detect an A/D conversion error, and feeds back a detection result to the A/D conversion unit as a control value to perform voltage control.