Built-in self-test
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A built-in self-test (BIST) mechanism within an integrated circuit is a function which verifies all or a portion of the internal functionality of the IC. For example, a BIST mechanism is provided in advanced fieldbus systems to verify functionality; also, many PC BIOSes include a BIST to perform a self-test of the PC's RAM on power-up.
Manufacturing test, as post-production chip testing is called, comprises a growing fraction of a modern IC device's total cost. Because of this, Design For Test (DFT) has shifted from an afterthought to a distinct design activity of a chip development cycle.
The main purpose of BIST is to reduce the complexity, and thereby decrease the cost and reduce reliance upon external (pattern-programmed) test equipment. BIST reduces cost in two ways: (1) reduces test-cycle duration, and (2) reduces the complexity of the test/probe setup, by reducing the number of I/O signals that must be driven/examined under tester control. Both lead to a reduction in hourly charges for automated test equipment (ATE) service.
Outside of manufacturing test, BIST can be designed to perform field-diagnostics of individual devices or entire systems. For example, at powerup, nearly all modern computer peripherals (printers, monitors, PCs) perform a limited self-diagnostic. Failure of the diagnostic is reported to the user.
There are several specialized versions of BIST which are differentiated according to what they do or how they are implemented:
- Programmable Built-In Self-Test (pBIST)[1]
- Memory Built-In Self-Test (mBIST) - e.g. with the Marinescu algorithm
- Logic Built-In Self-Test (lBIST)
- Analog and Mixed-Signal Built-In Self-Test (AMBIST)
