Abstract:In this brief, the monotone phase-response property of a two-dimensional (2-D) causal digital allpass filter (DAF) with real coefficients or complex coefficients in the quarter-plane (QP) support region is presented. Regarding the circumstance of real coefficients, we also prove that the previously proposed stability criterion on the viewpoint of unwrapped phase due to Pei and Shyu is necessary and sufficient for 2-D separable DAFs, but is only sufficient for QP DAFs. The resultant property possesses the advan… Show more
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