ADC Input Saturation Detection Using Diagnostic Threshold Signals
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Solution Overview
Problem
Analog-to-digital converters (ADCs) produce invalid data samples when the input voltage exceeds or falls below their valid range, leading to clipping, which can result in samples indistinguishable from valid data, causing errors in waveform representation.
Innovation Solution
A diagnostic circuit generates signals indicating whether input voltages meet thresholds, and a controller uses these signals to determine if the ADC is saturated, transitioning the sensor into a safe state to prevent output of faulty data by discarding or correcting samples near maximum or minimum values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the ADC operates without voltage range monitoring, then the device complexity is reduced, but the reliability deteriorates due to invalid data samples being produced when voltage falls outside the valid input range
Solution Approach 1:
The diagnostic circuit performs preliminary monitoring of the input voltage range before the ADC processes the signal. By continuously comparing the input voltage against predefined thresholds using voltage dividers and comparators, the system identifies saturation conditions in advance and prevents invalid data from being generated, thereby maintaining reliability without significantly increasing overall system complexity.
Solution Approach 2:
The patent introduces a diagnostic circuit as an intermediary component between the sensor and the ADC. This intermediary circuit includes voltage dividers and comparators that monitor the input voltage range and generate diagnostic signals to indicate saturation conditions, allowing the main ADC to operate without direct complexity increases while ensuring reliable data conversion.
2Reliability
If diagnostic signals are added to monitor input voltage, then the reliability is improved by detecting saturation, but the device complexity increases due to additional circuit components
Solution Approach 1:
The diagnostic function is implemented locally at the ADC input stage using dedicated voltage dividers and comparators that only monitor the specific input voltage range. This localized approach ensures reliability by detecting saturation conditions precisely where they occur, while minimizing the increase in overall device complexity by confining the diagnostic circuitry to a specific functional area rather than distributing it throughout the entire system.
Solution Approach 2:
The patent utilizes parameter changes in the input voltage (comparing against threshold values) to detect saturation conditions. By monitoring voltage parameters through simple comparator circuits rather than complex analysis, the system achieves improved reliability through effective saturation detection while keeping the complexity increase minimal, as the solution relies on fundamental electrical parameter comparisons rather than sophisticated processing.
3Reliability
If the controller transitions to safe state on every threshold breach, then the reliability is improved by preventing faulty data output, but the productivity decreases due to frequent data loss
Solution Approach 1:
The controller applies partial action by transitioning to the safe state only when diagnostic signals confirm actual saturation conditions, rather than reacting to every threshold breach. The system distinguishes between temporary voltage fluctuations and genuine saturation events, activating the safe state transition only when necessary to prevent faulty data output. This selective approach maintains reliability by preventing faulty data while minimizing unnecessary safe state transitions that would reduce productivity.
Solution Approach 2:
The system employs feedback mechanisms where the diagnostic circuit continuously monitors input voltage and provides diagnostic signals to the controller. The controller uses this feedback to intelligently determine when to transition to the safe state, balancing reliability and productivity by acting only when the feedback indicates genuine saturation conditions rather than responding to all threshold breaches indiscriminately.
Data Source
AI summary
According to aspects of the disclosure, an apparatus is disclosed comprising: a controller; an analog-to-digital converter (ADC) coupled to the controller, the ADC including an input terminal for receiving a sensor signal from a transducer; and a diagnostic circuit coupled to the input terminal of the ADC and to the controller, the diagnostic circuit being configured to: generate a diagnostic signal that indicates whether a voltage at the input terminal of the ADC meets a first threshold, and provide the diagnostic signal to the controller, wherein the controller is configured to: receive a data sample from the ADC, detect whether the data sample meets a second threshold, and transition the apparatus into a safe state when: (i) the diagnostic signal indicates that the voltage at the input terminal does not meet the first threshold, and (ii) the data sample meets the second threshold.