1 Introduction
In deep submicron design, many thousands of repeaters have to be used and those devices in general consume significant amounts of power and area and they can cause severe routing congestion and floorplanning problems. Moreover, unconstrained buffering might not even be sustainable into the future. In [5] it has been shown that, depending on some assumptions for the Rent exponent in statistical models for wire length distribution, unconstrained optimal buffering might require up to 80% of the total silicon area in future semiconductor technologies. Finally, designers must almost always seek a trade-off between performance, power, price and area.