Applying the Power Contributors Method in a complex CMOS cell

The evaluation of a circuit library in terms of leakage currents and static power consumption is obligatory for low power designs. It has to be done early in the design process and it requires significant time effort. Both the leakage currents and the static power consumption depend on many parameters, such as: process, dimensions, temperature, cell's input state and power supply voltage. In order to speed up the evaluation procedure, the Power Contributors method has been introduced. According to this method, any cell for any input state can be split up into elementary sub-circuits. By modeling all the leakages flowing onto these sub-circuits, expressions can be derived by just adding each contribution from each sub-circuit. This method has been applied here on an OAI22_X1 complex CMOS cell from NanGate library. Results are promising, since the mean relative error between the derived models and the results from HSPICE simulations is less than 1%.