Networked control systems (NCSs) are commonly modelled by the switched systems involving exponential non-linearities. A challenging problem is to obtain a tight linear approximation of the mentioned non-linear models to derive analysis and design criteria in terms of linear matrix inequalities (LMIs), which can be easily handled using the well-established algorithms. The present paper introduces a novel procedure to achieve an improved polytopic over-approximation of the non-linearities emerged in the modelling of NCSs. Moreover, stability of the NCSs is analysed to verify the merits of the proposed method; to this end, a benchmark numerical example is presented to illustrate the superior performance of the suggested approximation scheme compared with the existing approaches in the literature.