Great to have you back!
Not a member? Create an account
Great to see you here!
Already got an account? Sign in here
The pattern set is formatted into a test program that executes on the ATE, using JTAG as the communication backbone.
How easy is it to see the value of an internal node at the output pins? digital systems testing and testable design solution
Consider this statistic: For a complex System-on-Chip (SoC) manufactured on a 5nm process node, the cost of testing can account for 30% to 50% of the total manufacturing cost. If a defective chip escapes into the field—especially in automotive or medical applications—the cost of failure is not measured in dollars of repair, but in human lives. The pattern set is formatted into a test
The dominant solution for sequential circuits is scan testing. During normal operation, flip-flops act as state-holding elements. In test mode, these same flip-flops are reconfigured into a giant shift register, or "scan chain." Test vectors are shifted in serially, setting every internal flip-flop to a known state in just a few hundred clock cycles. After a single functional clock pulse captures the circuit's response, the result is shifted out for comparison. This elegantly converts a complex sequential test problem into a simpler combinational one. If a defective chip escapes into the field—especially
The process of generating tests involves two main steps: fault activation and fault propagation. To detect a fault, a specific logic value must be applied to the fault site (activation), and the resulting erroneous signal must be driven to an observable output pin (propagation). As circuit depth increases, this process becomes computationally expensive, a problem known as the "state explosion" in Automatic Test Pattern Generation (ATPG).
The insight is brilliant in its simplicity: Replace every standard flip-flop (or most of them) with a and connect them into one or more long shift registers called scan chains .
As clock frequencies rise, timing violations become critical. Delay faults model chips that function correctly at slow speeds but fail at operational speeds.
