A Scalable Scan Architecture for Godson-3 Multicore Microprocessor

This paper describes the scan test challenges and techniques used in the Godson-3 microprocessor, which is a scalable multicore processor based on the SMOC (Scalable Mesh of Crossbar) on-chip network and targets high-end applications. Advanced techniques are adopted to achieve the scalable, low-power and low-cost scan architecture at the challenge of limited I/O resources and large scale of transistors. To achieve a scalable and flexible test access, a highly elaborate TAM (Test Access Mechanism) is implemented with supporting multiple test instructions and test modes. Taking advantage of multiple cores embedding in the processor, scan partitions are employed to reduce test power and test time, and test compression with more than 10X compression ratio are utilized to decrease the scan chain length. To further decrease test time, a Data-Synchronous-Comparator (DSC) is proposed for comparing the scan responses of the identical cores.