On RTL Testability and Gate-Level Stuck-At-Fault Coverage Correlation for Scan Circuits

• http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6037434

testability, fault coverage, stuck at fault, register transfer level,
correlation, scan, digital, circuit

Major drawback of high level design methodologies such as RTL can be seen in the
following facts. First, they lack of sufficiently precise fault models - compared
to sophisticated models available for low level description levels such as
logic gate level. Second, since the structure of a design changes significantly
with every logic synthesis run, testability analysis is typically performed only
after final logic synthesis. As a consequence, results of the analysis could be
obtained when it is very costly to reflect them in the high level design.
The drawbacks can be removed in several ways. In the contribution, it is supposed
the analysis is performed at RTL and is efficient enough to be run after each
change in RTL design - giving a designer an immediate information about the
change impact to testability parameters. Under the assumption, following
requirements are posed to the analysis: low computational complexity and
accuracy. The latter requirement is met if strong correlation is detected between
RTL testability analysis results and low-level test pattern generation results.
In the paper, it is shown such a correlation exists although relatively simple
academic RTL testability analysis solution is compared to widely used commercial
gate-level test pattern generation solution. Detail results achieved during the
experiments over scan circuits are presented, discussed and summarized in the
paper.