Recursive digital filters which are free from subharmonics
M.J. Werter · International Journal of Circuit Theory and Applications · 1991
Abstract In recursive digital filters, quantization of signals can result in instabilities such as limit cycles and subharmonics. the aim of this paper is to analyse these instabilities in periodically excited recursive digital filters and to present methods to suppress the unwanted phenomena. A new type of digital filter structure is introduced which is free from subharmonics for discrete‐time periodic input signals with a given period N. Using the theory of cyclotomic polynomials, this structure is extended to suppress subharmonics for input signals which are periodic with a divisor of N. A general principle is described to convert a stable, autonomous state space digital filter into one which is free from subharmonics under any periodic excitation with a given period N.