Tri-State Coding Using Reconfiguration of Twisted Ring Counter for Test Data Compression

As technology processes scale up and design complexities grow, system-on-chip integration continues to rise rapidly. According to these trends, increasing test data volume is one of the biggest challenges in the testing industry. In this paper, we present a new test data compression method based on reusing a stored set with tri-state coding (TSC). For improving the compression efficiency, a twisted ring counter is used to reconfigure twist function. It is useful to reuse previously used data for making next data by using the function of feedback of the ring counter. Moreover, the TSC is used to increase the range information transmission without additional input ports. Experimental results show that this compression method improves a compression ratio and a test time on both International Symposium on Circuits and Systems'89 and large International Test Conference'99 benchmark circuits in most cases compared to the results of the previous work without a heavy burden on the hardware.