The benefits of built in self test for OEM designers

An important advantage of full speed Autonomous Built In Self Test over conventional test techniques can be established. Conventional test techniques,such as functional tests or scan path tests, are often carried out at low speed. Had these low speed tests been carried out on the FIR filter, the circuits would have incorrectly passed their test. Furthermore the defects would have been extremely difficult to diagnose. A further advantage of the Autonomous Built In Self Test on the FIR filter is that speed parameterisation of the circuit can occur. The FIR filter was specified to operate at 10 MHz. The majority of the circuits operated at this speed over the first four test phases. The clock speed could then be increased until the first four phases of these circuits began to fail. Some circuits began to fail at 13 MHz, whilst other circuits went on to operate at 17 MHz. It is therefore possible to classify these circuits by operating frequencies, all from the same production batch