This paper describes a fully automated low-power design methodology in which three different voltage-scaling techniques are combined together. Supply voltage is scaled globally, selectively, and adaptively while keeping the performance. This methodology enabled us to design an MPEG4 codec core with 58% less power than the original in three week turn-around-time.

We present a low-power design method that utilizes the multiple supply voltages. The proposed method reduces the power consumption of random logic circuits by 47% on the average, with up to 15% area overhead, by the combination of Clustered Voltage Scaling (CVS) and by Row optimized Power Supply (RRPS) scheme. By the CVS scheme, the optimal netlist, that uses the minimized number of the level converters and the maximized number of the low Vdd gates under the timing constraints, is generated. To avoid the wiring resource consumption and the increase of the interconnect delay caused by the layout constraints of the multiple-supply-voltage design, a new power bus wiring scheme called RRPS is proposed. The proposed method is applied to a media processor chip Mpact/sup TM/ and achieved the above mentioned results. In this paper, the emphasis is put on the interrelation between the generation of the two-supply-voltage netlist with the CVS scheme and the layout technology, such as the power supply scheme and the placement of the multiple-supply-voltage gates. The clocking scheme for the multiple supply voltages is also discussed.