An apparatus has a large block of synchronous logic arranged to include a first partition and a second partition. The first partition is configured to receive a first clock signal during a functional mode and during a test mode. The second partition is configured to receive the first clock signal during the functional mode, and the second partition configured to receive a second clock signal during a test mode. The second clock signal has the same frequency as the first clock signal. The second clock signal has a different phase from the first clock signal.