“…The criteria reported in Chen (2009), Kandanvli and Kar (2008, 2013), Kar and Singh (2004), Kokil and Kar (2012), Lee et al (2012) and Singh (1985) are not sufficient enough to comment about the stability of digital filters in the presence of external interference. In order to deal with the effects of the external disturbance in the digital filters, several stability conditions have been presented (Ahn, 2011; Kokil and Arockiaraj, 2016, 2017; Kokil and Shinde, 2015; Kokil et al, 2012, 2018b, 2019; Kumar et al, 2019; Li et al, 2012). Therefore, stability analysis of the digital filters under simultaneous presence of saturation nonlinearities, state-delay and external disturbance is an important problem.…”