Introduction to Hardware Testing

Traditional software tests do not cover all the hardware faults on a chip. Traditional methodologies have bottleneck which are critical chip area not covered under test, expensive testing, exhaustive and less efficient test strategy, difficult to test memory or logic array, stuck at fault not discovered during test and many more issues. To have a quality hardware we need to test it effectively and come up with a test strategy for the same. In this paper, a very effective and powerful testing methodology Built-in Self-Test (BIST) is being surveyed.

Built-in Self-Test (BIST) technique offers better test coverage. BIST is a highly effective technology with provides debug or verification testing, characterization, diagnosis, design debug, economical production test and many other functions.

BIST is a test design technique in which a part of the circuit is used to test the circuit itself. The part of the circuit executes a self- test and the results are analyzed. In this paper, detailed description about the how self-test is done, BIST architecture, its working and many other concepts are discussed.

Index Terms—BIST, built-in self-test, hardware design test, circuit testing, feedback circuits, hardware testing, automatic testing, digital integrated circuit testing, logic testing.

I. INTRODUCTION TO HARDWARE TESTING

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here is tremendous advancement in design and implementing hardware systems. A complex and very powerful system can be built using tools such as VHDL. Consequently there will be flaws in the system which could be incorrect requirement collection, design fault or critical hardware components under tested resulting in poor hardware system.

Typical hardware faults are stuck-at fault, transition fault, coupling fault and many more. These faults degrade the quality of the hardware and yields poor performance. We need to have an approach to test a chip for hardware fault.

In figure1 we get an idea about cost of fixing a defect, let the cost to find and fix a defect be x, if the defects are spotted at early stage say during requirement collection phase the cost incurred to fix the defect would be 5x. If the defect is found during the design state the cost to fix it would be 10x. If defects are found during building the product, the cost to fix will be 15x and defects found during testing will cost 20x.

To have an excellent product maximum defects should be caught before testing or during testing. Once the testing cycle is complete, if there is a defect it will be found in production and cost to fix the defect will be higher than the product cost.