Exploiting built-in delay lines for applying launch-on-capture at-speed testing on self-timed circuits

The application of scan-based at-speed delay testing on asynchronous circuits is not trivial. Their unorthodox design leaves them generally incompatible with traditional synchronous design and test tools, as well as standard automatic test equipment. The correct generation of at-speed test clocks and the use of conventional automatic test patterns generation (ATPG) tools are some of the problems that face the application of at-speed testing on asynchronous circuits. This paper presents a method of applying scan-based at-speed testing on single-rail bundleddata handshake-free (self-timed) asynchronous circuits by taking advantage of built-in delay lines. The proposed test method uses launch-on-capture scan-based testing with endpoint masking and generates the test patterns using conventional ATPG tools. The proposed test is applied on circuits in a self-timed microprocessor fabricated in 28nm FD-SOI CMOS technology. This method is validated by the reported test coverage and simulation results, along with post-silicon test results on a Teradyne FLEX tester.