A current-mode exponential amplifier

The authors present an analog circuit architecture that implements the function f(x, y)=x/spl middot/e/sup a/spl middot/y/, where f(/spl middot/,/spl middot/),x and y are expressed by currents. An important property of this circuit is that x and y may either be positive or negative. The design of this circuit is based on the translinear principle, and suits IC implementation. The motivation for the development of this circuit is the need for f(x, y) as a building block in a neural network; however, the use of this circuit is not limited to neural networks.