A CMOS analog circuit for Gaussian functions

A new current-mode CMOS analog programmable arbitrary nonlinear function synthesizer

“…(1) Only one or two functions can be realized at a time; see for example [1] for a sine function generator realization, [3] where the realization of a Gaussian function generator is proposed, [7] for the inverse sine and the inverse cosine functions realizations, [8] for the realization of exponential and logarithmic functions, [10] where the realization of a tangent hyperbolic sigmoid is proposed, [13] where a triangular/trapezoidal function generator is presented, [14] where a sinh resistor is proposed for tanh linearization, [16] which presents a power law function generation, [17] where a Gaussian/triangular basis functions computation circuit is proposed, [19] for a fully differential tanh function realization, [23] which presents a realization for the hyperbolic tangent sigmoid function, [24] where radial basis function circuits are presented and [25] for the realization of an inverse sine function realization. (2) Recourse to the use of piecewise linear approximations to approximate the required nonlinear function; for example in [5,6,15,20,22], where piecewise linear approximations are used to approximate, and whence, realize several nonlinear functions.…”

Fully Programmable Gaussian Function Generator Using Floating Gate MOS Transistor

“…The operating principle of conventional Gaussian circuit, proposed by Madrinas et al is described in [4]. The MOSFETs M3 and M4 of the conventional circuit, shown in Figure 4, are working in linear region and behave as variable resistors.…”

“…The effect of V F on output current and the Gaussian function is given by [4] I 0 = I R e −Iout/vT gdsd ,…”

“…But the conventional circuit has limitations of mismatching of MOS transistors and it can implement only half of the Gaussian function. The circuit proposed in [5] overcomes the limitations of the circuit proposed in [4] by using FGMOS transistors.…”

“…Madrinas et al proposed a CMOS analog integrated circuit to implement Gaussian function [4]. They have successfully designed a five-transistor circuit in which current mirror is in weak inversion region and voltage variable resistors are replaced by two MOS transistors.…”