Self-Testing Integrated Circuit Reference Voltage and Comparator
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Solution Overview
Problem
Integrated circuits used in safety-critical applications, such as power management controllers, often fail to detect defects during self-testing, leading to unreliable operation due to faulty comparators that fail to detect supply voltage ranges correctly.
Innovation Solution
A self-testing method and apparatus that utilize a digital-to-analog converter to provide a linear voltage ramp for testing the output voltage of a reference circuit and comparators, including a stuck-at test and voltage range test, with the ability to adjust the reference voltage and selectively couple an analog-to-digital converter in a loopback configuration for comprehensive testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional self-test mechanisms are used in power management controllers, then the testing process is simple and quick, but defects may be hidden and defective ICs may pass the self test
Solution Approach 1:
The patent applies preliminary action by performing a reference voltage test before the comparator functionality test. The reference voltage circuit is tested first to ensure it provides accurate voltage levels, and only if this test passes does the system proceed to test the comparators. This preliminary testing of the reference voltage source prevents false test results and ensures that subsequent comparator tests are valid, thereby improving defect detection accuracy without requiring complete redesign of the test architecture.
2Reliability
If comprehensive testing of the reference voltage circuit and comparators is performed, then reliable operation is ensured, but the testing time and complexity increase
Solution Approach 1:
The patent implements periodic action by dividing the comprehensive self-test into distinct sequential phases: first testing the reference voltage circuit, then testing the comparators only if the reference voltage test passes. This phased periodic approach ensures thorough testing for reliability while avoiding unnecessary testing steps that would waste time, thus optimizing the balance between operation reliability and self-test duration.
Solution Approach 2:
The reference voltage circuit is tested in advance before comparator testing. This preliminary action ensures that the foundation for accurate comparator testing is established first, preventing wasted time on subsequent comparator tests if the reference voltage is found to be defective. This sequencing reduces overall test time while maintaining comprehensive coverage of critical components.
3Reliability
If the reference voltage stability is not tested, then the test process is faster, but unreliable operation may result if comparators fail to detect the correct range
Solution Approach 1:
The reference voltage stability is tested in advance before comparator functionality is evaluated. This preliminary verification of voltage accuracy ensures that comparators will operate within correct ranges during their subsequent test, preventing unreliable operation. By establishing voltage stability first, the system ensures accurate detection without requiring repeated or extended comparator testing, thus maintaining testing efficiency.
Solution Approach 2:
The reference voltage circuit acts as an intermediary element that must be verified before the comparators can be properly tested. The patent introduces this intermediate testing step to ensure that the voltage reference, which mediates all comparator comparisons, is stable and accurate. This intermediary verification prevents propagation of errors through the test system while maintaining overall testing efficiency.
Data Source
AI summary
An integrated circuit and a method of self-testing the integrated circuit are provided. The method comprises: generating a reference voltage at an output of a reference circuit; initiating a test of the reference circuit during a test mode; determining whether the test of the reference circuit passes; and comparing, if the test of the reference circuit passes, a first voltage with the reference voltage. The disclosed test method provides for more complete testing of the integrated circuit.