Enhancing test on 3GHz designs with SSN

Broadcom's success with Tessent Streaming Scan Network

Broadcom implemented SSN on a design with 12 identical CPUs, running at over 2.5GHz. They found that testing the identical cores with SSN reduced overall test time by 15%. There was also a significant power benefit; their Shmoo plot showed a 30mV difference between SSN vs. EDT when testing 12 cores in parallel. This is possible with SSN, because shift and capture is done independently across the cores that are tested simultaneously, as shown in figure 1. With SSN, there was no difference in power whether 1 or 12 cores were tested at the same time. Finally, using SSN, they were able to run shift at twice the frequency (2X test time reduction).

Watch Srinu Alampally, Master Engineer at Broadcom, explain how they implemented SSN and share the silicon results on a high-speed multi-CPU design in this ITC 2021 presentation.