Token scan cell for low power testing

A multiphase clocking technique is presented for reducing the test power for scan-based circuits. A novel scan cell design called the token scan cell is developed, which combines a phase-generating flip-flop and a data flip-flop to overcome the inter-phase skew and clock routing problems. Experimental results show that on average ∼87% of the data transition count during scanning is reduced. For many circuits with long chains, a reduction of >98% can even be achieved.