A/D Converter Threshold Testing With Feedback Voltage Correction
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Solution Overview
Problem
Conventional A/D converter test systems require lengthy test times due to the need for multiple steps of analog voltage increments, leading to increased test costs and inefficiencies.
Innovation Solution
A test apparatus and method that outputs a 2N-valued analog voltage, with a signal processing unit to correct and asymptotically approach threshold voltages, reducing the number of captures needed by using a voltage generating unit, capture unit, and signal processing unit to compare output codes with expected values, allowing for reduced test time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of steps of analog voltage is increased to ensure accurate measurement of A/D converter characteristics, then measurement precision is improved, but test time increases significantly
Solution Approach 1:
The patent implements feedback by comparing the captured output code with the expected code and using the comparison result to correct the analog voltage for the next measurement. This feedback mechanism allows the system to converge to accurate threshold voltage values with fewer measurements, resolving the contradiction between measurement precision and test time by iteratively improving accuracy without requiring a large number of initial steps
Solution Approach 2:
The patent applies preliminary action by generating an initial analog voltage value before actual measurement begins. This preliminary voltage is then refined through feedback-based correction, allowing the system to start close to the target threshold voltage and require fewer measurement steps to achieve accurate results, thereby reducing test time while maintaining precision
2Reliability
If the full scale voltage range is designed wider than the A/D converter input range to account for margin of error, then reliability is improved, but test time increases
Solution Approach 1:
The patent segments the full scale voltage range into multiple discrete levels, where each level corresponds to a specific threshold voltage to be measured. By dividing the voltage range into manageable segments rather than treating it as a continuous wide range, the system can efficiently measure each threshold with appropriate margin of error while avoiding the need to test the entire expanded voltage range, thus maintaining reliability without excessive test time
3Measurement precision
If conventional test systems use 8 to 16 times the number of steps of the A/D converter, then measurement completeness is improved, but productivity decreases
Solution Approach 1:
The patent employs dynamic adjustment of the analog voltage based on feedback from code comparison. Instead of using a fixed large number of steps, the system dynamically corrects the voltage value iteratively, adapting the measurement process to converge on accurate threshold values with fewer steps. This dynamic approach maintains measurement completeness while significantly improving productivity by reducing the number of required measurements
Data Source
AI summary
A test apparatus configured to test an N-bit (N represents an integer) A/D converter is provided. A voltage generating unit outputs a 2N-valued analog voltage to the A/D converter. A capture unit captures an output code of the A/D converter for each level. A signal processing unit compares the output code captured for each level with the corresponding expected value code, corrects the value of the analog voltage for each level based upon the comparison result, and outputs the corrected analog voltage to the voltage generating unit.