In this paper, an on-chip clock (OCC) controller with bypass function based on an internal phase locked loop (PLL) is designed to test the faults in system on chip (SOC), such as the transition-delay faults and the stuck-at faults. A clock chain logic which can eliminate the metastable state is realized to generate an enable signal for the OCC controller, and then, the test pattern is generated by the automatic test pattern generation (ATPG) tools. Next, the scan test pattern is simulated by the Synopsys tool and the correctness of the design is verified. The result shows that the design of at-speed scan test in this paper is high efficient for detecting the timing-related defects. Finally, the 89.29 percent transition-delay fault coverage and the 94.50 percent stuck-at fault coverage are achieved, and it is successfully applied to an integrated circuit design.
