ADC Gain And Offset Diagnosis Using Startup Signal Thresholds
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Solution Overview
Problem
Existing sensor circuits face challenges in accurately diagnosing offset and gain errors in analog-to-digital converters (ADCs) used in sensor applications, particularly due to random failures and drift effects that can mimic faulty behavior.
Innovation Solution
The implementation of a sensor circuit with a startup phase and an operation phase, featuring an offset diagnosis circuit and a gain diagnosis circuit. These circuits include low pass filters, registers, and comparator circuits that set threshold ranges based on startup signal values, allowing for real-time monitoring and error detection during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If real-time monitoring and error detection are implemented during operation, then reliability is improved, but device complexity increases due to additional diagnosis circuits
Solution Approach 1:
The diagnosis function is segmented into separate offset diagnosis circuit and gain diagnosis circuit, each with dedicated low pass filters, registers, and comparator circuits. This segmentation allows independent monitoring of different error types without requiring a monolithic complex diagnosis system.
Solution Approach 2:
The system performs preliminary action by capturing startup signal values in registers during the startup phase, before normal operation begins. These captured values serve as reference thresholds for subsequent error detection during operation, enabling real-time monitoring without requiring complex continuous calibration systems.
2Measurement precision
If threshold ranges are set based on startup signal values, then measurement precision is improved for error detection, but difficulty of detecting and measuring increases due to drift effects
Solution Approach 1:
The system captures the startup signal values in registers during the startup phase before normal operation begins. These captured values serve as reference thresholds for subsequent error detection. By establishing the baseline beforehand, the system can distinguish between normal drift during operation and actual offset/gain errors, improving measurement precision while managing the complexity of drift differentiation.
Data Source
AI summary
A sensor circuit, having a startup phase and an operation phase, includes: a sensor configured to generate a sensor signal based on a measured property, wherein the sensor signal has a frequency spectrum defined by a first frequency and a second frequency that is greater than the first frequency; a signal processing circuit including an analog-to-digital converter (ADC) configured to convert the sensor signal into a digital sensor signal; and an offset diagnosis circuit. The offset diagnosis circuit includes: a low pass filter having a cutoff frequency less than the first frequency and configured to generate a filtered signal based on the digital sensor signal; an offset register configured to store a startup signal value of the filtered signal during the startup phase; and an offset comparator circuit configured to set a threshold range based on the startup signal value for use during the operation phase.