A study of designing recursive 2-D digital filter from an analog bridged-T network

This paper proposes a new technique of designing 2-D recursive digital filters starting from a doubly-terminated analog bridged- T network. This network contains inductive and capacitive reactance elements in s₁ and s₂ domains. The different possibilities are examined . When compared with the fourth order Butterworth polynomial, only three possibilities exist and the corresponding impedances are obtained. Starting with such an analog bridged-T network, 2-D filters are obtained through the application of double generalized bilinear transformations with the coefficients in the specified ranges to ensure stability. Different filter outputs can be obtained, depending on the starting network and the coefficients of the generalized bilinear transformations