Sensor Output Buffer Diagnostics Using Duplicate Resistive Networks
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Solution Overview
Problem
Sensor output buffer stages in electronic circuits, such as current sensors, often experience errors in offset or gain that affect measurement accuracy, and existing technologies fail to effectively detect and report these errors within safety thresholds specified for automotive safety standards like ASIL.
Innovation Solution
An output buffer diagnostic circuit is introduced, featuring a duplicate resistive network that replicates the sensor output buffer's topology, producing a differential duplicate signal indicative of error conditions, and includes averaging and error comparison circuits to detect and report errors, ensuring operation within specified safety limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a duplicate resistive network is added to monitor output buffer errors, then measurement precision and safety compliance are improved, but device complexity increases
Solution Approach 1:
The patent implements a duplicate resistive network that replicates the topology and resistor ratios of the original output buffer resistive network. This copy processes the differential input signal independently to generate a duplicate output signal, which is then compared against the actual output buffer signal to detect gain and offset errors. The copying approach enables error detection without fundamentally changing the original buffer architecture.
Solution Approach 2:
The diagnostic function is segmented into separate functional blocks: the duplicate resistive network, the averaging circuitry, and the error comparison circuit. This segmentation allows each component to perform its specific function independently, making the overall system more manageable and maintainable while enabling precise error detection through dedicated comparison logic.
2Measurement precision
If averaging circuitry is used to reduce noise in error detection, then measurement precision is improved, but response time increases
Solution Approach 1:
The averaging circuitry periodically samples and accumulates the difference between the duplicate output signal and the actual output buffer signal. By performing multiple measurements over time and averaging the results, the circuit reduces the impact of random noise and transient disturbances, thereby improving measurement precision while maintaining a controlled response time through the periodic averaging process.
Data Source
AI summary
Output buffer diagnostic circuits for monitoring a sensor output buffer include a duplicate resistive network corresponding to a resistive network in the monitored sensor output buffer. The duplicate resistive network may include the same or similar topology as the output buffer resistive network. The duplicate resistive network is configured to produce a differential duplicate signal indicative of when an error condition exits in the sensor output buffer. The diagnostic circuit can include averaging circuitry configured to receive the differential duplicate signal and produce an average duplicate signal. The diagnostic circuit can include an error comparison circuit configured to receive the average duplicate signal and detect when the average duplicate signal exceeds a nominal or preset error value corresponding to an error condition in the sensor output buffer. The error comparison circuit is configured to produce an error indication when the average duplicate signal exceeds the preset error value.