I. Introduction
In recent years, the study of Hopfield neural networks has attracted considerable attention since it plays an important role in applications such as classification of patterns, associative memories and optimization. To the best of authors' knowledge, in neural processing and signal transmission, significant time delays as a source of instability and bad performance may occur. Therefore, the stability analysis problem of Hopfield neural networks with time-delay has been attracted a large amount of research interest and many sufficient conditions have been proposed to guarantee the asymptotic or exponential stability for the neural networks with various type of time delays such as constant, time-varying, or distributed, see for example, [16], [17], [18], [21]~[25], [27]~[31] the references therein.