SAR ADC Self-Test Circuit for Internal Failure Diagnosis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing analog-to-digital converters require external circuits for testing, which is inconvenient and may not provide detailed failure diagnosis, especially in critical applications like the automotive field where high reliability is needed.
Innovation Solution
A successive-approximation analog-to-digital converter that can perform self-testing by utilizing its internal components, including capacitors and digital-to-analog converters, to detect failures and pinpoint the location of degradation without external circuits, allowing for integrated self-diagnosis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external circuits are used for testing the analog-to-digital converter, then the testing function is provided, but additional dedicated circuits are required and complex modifications are needed
Solution Approach 1:
The analog-to-digital converter is designed to perform both its primary conversion function and self-testing function using the same internal components. The converter can operate in normal mode for analog-to-digital conversion and in test mode for self-diagnosis, eliminating the need for separate external testing circuits and achieving multi-functionality with existing components.
Solution Approach 2:
The analog-to-digital converter performs self-testing by utilizing its own internal components to detect failures and diagnose issues within itself. The device serves its own testing needs by comparing conversion results obtained through different operational sequences, enabling autonomous fault detection without requiring external dedicated testing equipment.
2Reliability
If external circuits are used for testing, then failure detection is possible, but detailed failure location information is not provided
Solution Approach 1:
The system implements feedback by comparing the digital output values obtained from two different operational sequences. By analyzing the differences between these results, the system can not only detect that a failure has occurred but also identify the specific location of the failure within the converter components, providing detailed diagnostic information.
Solution Approach 2:
The testing process is divided into distinct operational sequences where different components are activated in specific patterns. By segmenting the conversion process into multiple testable sequences and comparing results, the system can isolate and identify the specific component or stage where a failure occurs, providing precise failure location information.
3Device complexity
If the converter uses internal components for self-testing, then no additional external circuits are needed, but the converter must support multiple operational modes
Solution Approach 1:
The control logic is designed to manage multiple operational modes (normal conversion mode and test mode) using the same physical hardware. By implementing mode selection and control mechanisms, the converter can switch between different operational sequences, enabling self-testing functionality without requiring separate external testing equipment, thus achieving multi-functionality with a unified circuit design.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables reliable self-testing within the converter, providing both failure indication and location, thus enhancing operational safety and reducing the need for complex external testing setups, particularly beneficial in safety-critical applications.
Implementation Method 1
a first generator (20) comprising an output terminal (2) and having the function of performing the sampling of the input analog value Vin when the analog-to-digital converter (1) is such to operate in the sampling phase of the normal operation mode, and having the function of performing the conversion from the digital value SN into an analog value when the analog-to-digital converter (1) is such to operate in the conversion phase of the normal operation mode; moreover the first generator (20) is such to generate at the output terminal (2) a first analog value (Vx) as a function of a configuration signal S3
Implementation Method 2
a digital-to-analog converter (40) comprising an output terminal (3) for generating an analog value when the analog-to-digital converter (1) is such to operate in normal operation mode; moreover, the digital-to-analog converter (40) is such to generate at the output terminal (3) a second analog value as a function of a control signal S1 when the analog-to-digital converter (1) is such to operate in the phase of execution of the successive-approximation algorithm of the test operation mode
Implementation Method 3
a second generator (30) for receiving an analog value from the output terminal (2), an analog value from the output terminal (3) and generating a digital value SN by means of a successive-approximation algorithm
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
It is described a successive approximation analog-to-digital converter (1). The analog-to-digital converter comprises a first generator (20) of a first analog value (S6) according to a configuration signal (S3), when the analog-to-digital converter is operating in a first phase (t0, t1, t2, t3, t4) of a test mode, comprises a digital-to-analog converter (40) adapted to generate a second analog value (S7) according to a control signal (S1), when the analog-to-digital converter is operating in a second phase (t5, t6, t7, t8) of the test mode, comprises a second generator (30), from the comparison of the first analog value with respect to the second analog value, of a digital value (SN) according to a successive-approximation algorithm, when the analog-to-digital converter is operating in the second phase of the test mode. The analog-to-digital converter further comprises a controller (50) adapted to receive a signal (S4) indicating the test mode; the controller is adapted to generate in the first phase the configuration signal (S3), is adapted to receive in the second phase the digital value (SN) and generate therefrom the control signal (S1) for controlling the generation of the second analog value according to the successive-approximation algorithm, and it is adapted to generate, from the digital value, an alarm signal (S5) indicating a failure within the analog-to-digital converter or indicating a degradation of the performance of the analog-to-digital converter.