Calibrated PWM Sensor Output Without Complex D/A Converters
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Solution Overview
Problem
Existing sensor devices for measuring variable physical quantities, such as temperature and humidity, face accuracy issues due to component variations, leading to inconsistent measurement values across devices, and require complex D/A converters for accurate PWM signal generation.
Innovation Solution
A sensor device comprising a digital signal processor and an amplifier that uses device-specific correction parameters stored in memory to preprocess raw sensor signals into pulse-width-modulated output signals, which are then converted into analog voltage or current signals, reducing circuit complexity and ensuring high accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex D/A converters are used to generate accurate PWM signals with correction values, then measurement precision is improved, but device complexity increases significantly
Solution Approach 1:
The patent replaces the analog D/A converter system with a digital signal processing system. Instead of using analog components to generate PWM signals, the invention uses a digital signal processor to directly generate PWM signals from digital correction values stored in memory. This substitution of digital for analog systems eliminates the need for complex D/A converters while maintaining measurement accuracy.
Solution Approach 2:
The patent performs correction value determination in advance during an adjustment mode before actual measurements are taken. The correction values are stored in memory and then used by the digital signal processor to generate accurate PWM signals without requiring real-time complex processing. This preliminary preparation of correction data simplifies the measurement process.
2Measurement precision
If analog signal-processing components are used to generate PWM signals, then measurement precision can be maintained, but manufacturing precision deteriorates due to component variations
Solution Approach 1:
The patent replaces analog signal-processing components with a digital signal processor. This eliminates the sensitivity to component variations such as voltage drifts and resistance tolerances that affect analog components. The digital system processes signals through software algorithms, ensuring consistent behavior across different devices regardless of manufacturing variations in electronic components.
Solution Approach 2:
The patent changes the operating parameters of the signal processing system from analog to digital domain. By performing signal processing and PWM generation in the digital domain using a microcontroller or digital signal processor, the system becomes insensitive to analog component parameter variations while maintaining measurement accuracy through software-based correction.
3Measurement precision
If high-resolution D/A converters are used to meet higher accuracy requirements, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent eliminates the need for high-resolution D/A converters by performing PWM signal generation directly in the digital domain. The digital signal processor generates PWM signals with the required resolution through digital logic operations, removing the need for separate high-resolution conversion stages and their associated complexity.
Data Source
AI summary
A sensor device includes at least one sensor, a digital signal processor and an amplifier. The at least one sensor is configured to measure a variable physical quantity and provide a raw sensor signal at an output of the at least one sensor. The digital signal processor is configured to preprocess the raw sensor signal output by the at least one sensor into a sensor signal and to further process the sensor signal into a pulse-width-modulated output signal having a duty cycle that is dependent on the measured quantity using a plurality of device-specific correction parameters stored in a memory to convert the sensor signal into the pulse-width modulated output signal. The amplifier is configured to convert the pulse-width modulated output signal into an analog voltage or current signal.