Electrical Optimization of PLAs

This work addresses the problem of improving an nMOS PLA's speed and power consumption through modifications to the transistor sizes in the PLA. A simplified model of gate delay (lumped RC model) is used that allows rapid estimation of delays thus allowing interactive computation of optimal transistor sizes. Algorithms are presented for: a) minimization of delay through the PLA b) minimization of power consumption subject to a bound on maximum delay. Both these minima are computed subject to bounds on the transistor sizes. A prototype electrical optimization tool was compared to the PLA generation tools in the Berkeley CAD tools package (eqntott and tpla). The maximum delay through a PLA can often be reduced by a factor of 2, and power consumption along the critical paths can be reduced by 10 - 30% without increasing maximum delay.