Analog Compatible Logic Functions Using EXCCIIs and an Extended Application for Sigmoid Activation Function

Abstract

This paper introduces the use of an extra X current conveyor (EXCCII) for realizing logic operations, suited for mixed signal design, without necessitating separate digital blocks. The NOR and OR logic functions are thus shown to be realized using the current-mode analog building block operable at a low voltage. The use of [Formula: see text][Formula: see text]V supply makes the new circuits operable at low voltage. The EXCCII bias current used in the design is 25[Formula: see text][Formula: see text]A. The input currents for defining logic 0 and logic 1 are, respectively, taken as 0[Formula: see text]mA and 0.5[Formula: see text]mA. The proposed circuits’ delay is found to be 10[Formula: see text]ns for low-to-high transition, while 2[Formula: see text]ns for high-to-low transition for NOR gate under capacitive loading conditions. The use of the current-mode approach makes the new proposed circuit apt for current-mode signal processing. The new proposed logic function circuits are compatible with analog circuits, thus providing an easy merger for mixed signal systems design, paving the way to a modular design approach. As an extended application in artificial neural networks, the proposed circuit is shown to generate a sigmoid activation function with convincing results. Several results are included by varying the reference current, and the circuit’s robustness aspect is also tested in the presence of fluctuation in the bias current of EXCCII. The novel approach of utilizing an analog building block for realizing digital functions is, therefore, verified with promising future applications.