A semiconductor device includes a first dummy group having a first set of dummy transistors; a first delay cell having a first set of active transistors; a second delay cell having a second set of active transistors; a second dummy group having a second set of dummy transistors; and relative to a first direction the first and second dummy groups and the first and second delay cells being arranged in a first sequence arranged as the first dummy group, the first delay cell, the second delay cell, and the second dummy group; and the first and second delay cells being free from having another dummy group therebetween.