Microwave passive circuits with multi-functional capabilities (e.g., simultaneous bandpass-filtering and power-division properties) have recently emerged as a suitable solution for the design of high-frequency compact devices with enhanced RF performance. Some of these RF components are based on signal-interference principles, so that their ideal power scattering parameters are frequency periodic and can be exactly matched to the frequency response of digital systems. The procedure to derive the coefficients of these discrete-time representations is expounded in this work, leading to the observation of zero-pole cancelations in the complex plane Z. For practical validation, the developed method is applied to a single-band Wilkinson-type filtering power divider and to a dual-band filtering impedance transformer.