Computational circuits using bulk-driven MOS devices

Four computational circuits realized for MOS technology, implementing multiplier/divider, exponential, squaring functions and Euclidean distance will be presented. The multiplier/divider circuit is designed using bulk-driven subthreshold- operated MOS transistors in order to reduce the circuit complexity and to respond, also, to the low-power requirements. The circuit output current is independent on process parameters. A new method for reducing the approximation error caused by a limited expansion in Taylor series of the exponential function will be presented, having the advantage of obtaining a very good frequency response as a result of the operation in saturation of MOS transistors. The MOS implementation of the squaring function based on a new principle using the arithmetic mean of the input potentials, as well as an original realization of the Euclidean distance function independent on technological parameters will be further described.