Observationsand MotivationTest patterns'power consumptions varysignificantlyOnly afew“care-bits"necessary for a test patterntodetect all thefaults covered by itApplyinghigh-power patterns at a partitionedsubcircuit containing all their care-bits reduces testpowerwithoutfaultcoverageloss
Observations and Motivation ◼ Test patterns’ power consumptions vary significantly ◼ Only a few “care-bits” necessary for a test pattern to detect all the faults covered by it ◼ Applying high-power patterns at a partitioned subcircuit containing all their care-bits reduces test power without fault coverage loss
Virtual Circuit PartitioningCircuitunderTestScanchainScan chainScan chainP1Glue LogicHigh-powerLow-powerPatternsPatternsScanchainScan chainP2
Virtual Circuit Partitioning High-power Patterns Glue Logic Circuit under Test Scan chain Scan chain Scan chain P1 Scan chain Scan chain P2 Low-power Patterns
ProblemDefinitionHowto partitionthecircuit suchthatthe“"care-bits"ofasmany as possible high-powerpatterns belong to a single partition?
Problem Definition ◼ How to partition the circuit such that the “care-bits” of as many as possible high-power patterns belong to a single partition?
Design FlowStart(with given specifiedpatterns)Rank test patterns based on capture powerFault simulationIdentify care-bits for the high-power patternsIteratively partition the circuitYesMeetconstraintsNoEnd
Design Flow Start (with given specified patterns) Rank test patterns based on capture power Fault simulation Identify care-bits for the high-power patterns Iteratively partition the circuit Meet constraints End Yes No
Care-Bits IdentificationLet low-power patterns detect as many faults aspossibleResponsecare-bits:faultsimulationStimulus care-bits:limitedimplicationICostfunction,dependson:Care-bitsselectedbypreviouspatternsComparisonbetweendifferentresponsecare-bits
Care-Bits Identification ◼ Let low-power patterns detect as many faults as possible ◼ Response care-bits: fault simulation ◼ Stimulus care-bits: limited implication ◼ Cost function, depends on: ◆Care-bits selected by previous patterns ◆Comparison between different response carebits