A current-mode exponential amplifier

This brief presents an analog circuit architecture that implements the function f (x, y) = x . e(A.y), where f (., .), 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. 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.