Comments on “Modified criterion for global asymptotic stability of fixed-point state-space digital filters using two’s complement arithmetic” [Automatica 46 (2010) 475–478]

A recently reported criterion [Singh V. (2010). Modified criterion for global asymptotic stability of fixed-point state-space digital filters using two’s complement arithmetic. Automatica, 46, 475–478], which is a modified version of an earlier criterion due to Mills–Mullis–Roberts, for the global asymptotic stability of fixed-point state-space digital filters with two’s complement arithmetic is reviewed. Pertaining to second-order digital filters, it is shown that Singh’s approach will never lead to a larger overflow stability region in the parameter space as compared to that obtainable via Mills–Mullis–Roberts criterion.