The application relates to the testing of electrical circuits, such as integrated circuits.
Test instruments are used to test electrically the ability of a fabricated circuit to perform its intended function. Instruments designed for testing integrated circuits usually operate in conjunction with other devices, such as computing devices. These instruments and other devices collectively are referred to as integrated circuit test systems or test systems.
A characteristic feature of conventional test systems is that they include a master clock signal or several master clock signals, and they also tend to include at least one synchronization signal that is distributed globally, either simultaneously or in sequentially staged pipelines, to all testing circuits for the purpose of indicating when a test is to begin.
Tests of integrated circuits typically involve applying specified stimuli to one or more pins of the circuits and then determining the results by applying signals on one or more pins of the circuits to appropriate measuring instruments. A test system generally incorporates all necessary testing circuits in close proximity to the circuit or circuits being tested, which are driven by an external controller that communicates test requirements to, and collects test results from, testing circuits of varying functions. The function of a testing circuit can be the generation of any stimuli or collection of stimuli and the conducting of any measurement or collection of measurements as required by testing specifications for the circuit or circuits being tested.