Clock-skew constrained placement for row based designs

In this paper we address the problem of placement of standard cells under the constraints of minimizing the clock-skew. We propose a quadratic programming based methodology for placement that not only results in an area and timing wise good placement but also a supporting zero-skew clock routing tree. Under the clock-skew constraints, our method produces significant reduction in the cost of zero-skew clock routing tree. During placement, we are able to obtain significant speed-up due to variable reduction and constraint modification.