Principles of complex wave digital filters
Alfred Fettweis · International Journal of Circuit Theory and Applications · 1981
Abstract The theory of real wave digital filters (WDFs) is extended to complex WDFs. A fundamental requirement turns out to be that of one‐realness, a complex impedance in the reference filter being called one‐real if it is real for Ψ = 1, where Ψ is the equivalent complex frequency. The only new components then required are complex multipliers with unimodular coefficients, but the adaptors are just as in the real case. The stability properties known for real WDFs can, in this way, also be extended.