Design of canonic wave digital filters using Brune and matched 4-port adaptors

In this paper, we present a new derivation of an adaptor for the well-known Brune section. It is shown that finite wordlength binary solutions exist for the Brune adaptor with the canonic number of quantized parameters. Furthermore, by giving up one degree of freedom, a much simplified matched 4-port adaptor (all diagonal elements of the scattering matrix are zero) is derived. It is shown that for a particular termination of the ports, the matched 4-port reduces to the wave digital lattice adaptor. Several examples utilizing matched 4-port adaptors in configurations other than the lattice are presented, all of which show excellent properties as well as being computationally very efficient.