Absolute Voltage Measurement Circuit With Digital Stress Compensation
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Solution Overview
Problem
Existing analog-to-digital converters (ADCs) are sensitive to mechanical stress and require precise reference voltages for accurate absolute voltage measurements, which can drift over time and are affected by packaging and soldering processes.
Innovation Solution
A circuit that calculates absolute voltage measurements in the digital domain using digital representations of reference values, reducing sensitivity to mechanical stress and eliminating the need for precise long-term stable reference voltages by using a formula that compensates for temperature variations and mechanical stress, allowing for simpler arithmetic operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a precise reference voltage is used for accurate voltage measurement, then measurement precision is improved, but the circuit becomes sensitive to mechanical stress and drift over time
Solution Approach 1:
The patent replaces the mechanical/analog reference voltage system with a digital computation system. Instead of relying on a physical reference voltage that drifts under mechanical stress, the system uses an ADC to digitize the voltage and then computes the absolute value digitally using stored calibration data and compensation algorithms, eliminating the mechanical stability requirements
Solution Approach 2:
The patent changes the measurement parameter from direct analog voltage comparison to digital computation of absolute voltage. By converting the voltage to digital form and using computational methods with temperature compensation and drift correction, the system achieves stable measurements without requiring a stable reference voltage
2Reliability
If a bandgap voltage reference is used to reduce drift, then long-term stability is improved, but the circuit complexity increases due to additional regulation components
Solution Approach 1:
The patent extracts the reference voltage generation function from the analog domain and moves it to the digital domain. Instead of including a bandgap reference circuit and associated regulation components, the system takes out the reference function and implements it through digital computation using stored calibration values and algorithms
Solution Approach 2:
The patent substitutes the complex analog bandgap reference circuitry with a digital computation system. The physical reference voltage generation and regulation mechanisms are replaced by digital algorithms that compute reference values from ADC measurements and calibration data
3Measurement precision
If analog amplification is used to enhance signal, then sensitivity is improved, but offset and gain variations occur due to mechanical stress
Solution Approach 1:
The patent replaces analog amplification with digital signal processing. Instead of using analog amplifiers that exhibit offset and gain variations under mechanical stress, the system uses digital computation to enhance and process the digitized signal, eliminating the harmful effects of mechanical stress on amplification
Data Source
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AI summary
A method and a circuit (300) for measuring an absolute voltage signal (vin), the circuit comprising: an A/D convertor (ADC), and a controller (302) adapted for: a) obtaining a first digital reference value (VPTAT) for a first reference signal (vptat) having a positive temperature coefficient; b) obtaining a second digital reference value (VBE) for a second reference signal (vbe) having a negative temperature coefficient; c) obtaining a raw digital signal value (VIN) for the signal (vin) to be measured, while applying a same reference voltage (vref) for step a) to c); and d) calculating the absolute voltage value (VABS) in the digital domain using a mathematical function of the first and second digital reference value (VPTAT, BE), and the raw digital signal value (VIN).