Verification Protocol
Verification procedures that execute circuit logic at the full design clock frequency ensure that timing margins and propagation delays meet operational specifications. An at-speed functional test confirms that high-speed transitions occur within the allotted clock cycle, identifying failures that static or slow-speed testing cannot detect. This verification method targets dynamic faults like crosstalk or ground bounce that only appear when signals switch at their intended rates.
Logic gates might function correctly during low-frequency boundary scan yet fail when required to switch at gigahertz speeds.
Execution Timing
Specialized automated test equipment generates precise pulse patterns to stimulate the board under conditions that simulate its end-use environment. By applying at-speed functional test vectors, engineers observe the physical behavior of the interconnects under realistic thermal and electrical stress. High-performance processors and memory modules often require these tests to validate the synchronization of data across parallel buses.
Failure Logic
Subtle manufacturing defects such as resistive vias or poor solder wetting create signal delays that exceed the setup and hold time requirements of the receiving components. Because these delays are minute, an at-speed functional test provides the only reliable way to catch marginal hardware that would otherwise cause intermittent system crashes. Timing violations at the assembly level indicate a mismatch between the fabrication tolerances and the design requirements.
