For designing nth-order digital filters from an active reference configuration comprising generalised-immittance convenors and resistors, a method proposed in earlier work makes use of second-order filter sections as building blocks in a cascade synthesis. A direct approach for designing such filters is presented in this letter. The proposed method yields a new class of wave digital filters distinct from the already known structures which are based on the doubly-terminated LC networks. © 1988, The Institution of Electrical Engineers. All rights reserved.