Self-Calibrating Voltage Divider for Parts Per Billion Accuracy
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Solution Overview
Problem
Current electrical measurement and calibration systems face challenges in achieving parts per billion accuracy due to the limitations of simple passive elements like voltage dividers, which require calibration at higher frequencies and varying environmental conditions.
Innovation Solution
A self-contained voltage divider system with a microprocessor, input and output selectors, a switching circuit, and a calibration bridge that allows for automatic calibration using a null detector circuit, enabling precise calibration and adjustment of voltage dividers for high accuracy measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple passive elements like voltage dividers are used, then device complexity is reduced, but measurement precision deteriorates due to inability to maintain accuracy at parts per billion level
Solution Approach 1:
The voltage divider system performs self-calibration using an integrated calibration circuit and microprocessor. The system automatically compares the voltage divider output against a reference voltage and adjusts the calibration stored in memory without external intervention, enabling the device to maintain high precision independently
Solution Approach 2:
The system changes the electrical parameters of the voltage divider by storing calibration factors in memory that compensate for drift and aging effects. The microprocessor applies these calibration factors to adjust the measured values, maintaining parts per billion accuracy despite changes in component characteristics over time
2Device complexity
If calibration is performed manually, then device complexity is reduced, but productivity deteriorates due to time-consuming calibration processes
Solution Approach 1:
The calibration process is automated through a microprocessor-controlled system that automatically compares the voltage divider against a reference, calculates calibration factors, and stores them in memory without requiring manual intervention or external calibration equipment
Solution Approach 2:
The system performs calibration automatically before each measurement session, ensuring the voltage divider is already calibrated and ready for high-precision measurements. This preliminary automated calibration eliminates time-consuming manual procedures and ensures accuracy is maintained throughout the measurement process
3Ease of operation
If voltage dividers are used without calibration, then ease of operation is improved, but measurement precision deteriorates due to drift and environmental variations
Solution Approach 1:
The system automatically maintains calibration by comparing the voltage divider output against a stable reference voltage and updating calibration factors in memory, eliminating the need for user intervention while ensuring continuous high precision despite environmental variations
Solution Approach 2:
The microprocessor continuously monitors the voltage divider performance and uses feedback from the reference voltage comparison to adjust and update calibration factors, ensuring the system maintains parts per billion accuracy by compensating for drift and environmental effects
Data Source
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AI summary
Resistor voltage dividers are commonly used to create reference voltages, or to reduce the magnitude of a voltage so it can be measured. Many measurements in test and measurement or calibration applications regularly require accuracies within the sub-part per million (ppm) range, e.g. 0.1 ppm to 1.0ppm. However, the continued drive for improved accuracy in calibration, standards, and measurements on circuits and components means many measurements and measurement systems are operating at 50 parts per billion (ppb) and below to approximately 10ppb. At these levels even relatively simple passive elements such as voltage dividers cannot be used without calibration and that these calibrations may be required at frequencies substantially higher than the other elements within the test and measurement equipment. Accordingly, the inventors have established a self-contained voltage divider with internal calibration allowing the voltage divider to be calibrated for every measurement if necessary.