Power reduction and technology mapping of digital circuits using AND-Inverter Graphs

The minimisation of power consumption is an important design goal for digital circuits. The switching activity of a CMOS digital circuit significantly contributes to overall power dissipation. By approximating the switching activity of circuit nodes as internal switching probabilities using AND Inverter Graphs (AIGs), it is possible to estimate the dynamic power dissipation characteristic of circuits. A technique for minimising the overall sum of switching probabilities is presented. The method is based on local reordering and swapping of nodes in AIG representing the functionality of the circuit to be realised. This paper also focuses on the problem of mapping a technology independent circuit to a specific technology, using specific gates and cells (AND cells, inverters and buffers) from a given library, with power as the optimisation metric. The resulting circuit that is obtained by mapping the AIG after switching probability optimisation has shown in simulation reduced power dissipation characteristic without an area penalty.