Design Space Exploration for Approximate Implementations of Arithmetic Data Path Primitives

While a detailed analysis of various approximation strategies for elementary arithmetic circuits (such as adders and multipliers) is widely covered in the literature, much less is known about approximate arithmetic data path primitives (such as Dot Product (DP) to name one example) because it is difficult to exactly analyze their error and other parameters. We provide a detailed analysis of approximation options if a two-dimensional DP circuit is implemented using pre-characterized approximate arithmetic circuits available in existing libraries of approximate circuits. We propose a method capable to cheaply estimate properties of candidate approximate implementations of DP circuit. By a careful selection of approximate components, hundreds of approximate DP circuits showing excellent tradeoffs between key design objectives were obtained.