A circuit is disclosed for testing memories using multiple built-in self
test (BIST) controllers embedded in an integrated circuit (IC). The BIST
controllers are brought to a synchronization point during the memory test
by allowing for a synchronization state. An output signal from an output
pin on the IC indicates the existence of a synchronization state to
automated test equipment (ATE). After an ATE receives the output signal,
it issues a resume signal through an IC input pin that causes the
controllers to advance out of the synchronization state. The ATE controls
the synchronization state length by delaying the resume signal.
Synchronization states can be used in parametric test algorithms, such as
for retention and IDDQ tests. Synchronization states can be incorporated
into user-defined algorithms by software design tools that generate an
HDL description of a BIST controller operable to apply the algorithm with
the synchronization state.