RC sequence asymmetric polyphase networks for RF integrated transceivers

Resistance-capacitance (RC) sequence asymmetric polyphase networks have recently gained a renewed interest in the design of radio-frequency integrated transceivers. These networks provide an efficient way for wideband quadrature signal generation with reduced sensitivity to component mismatch. In addition, polyphase networks represent a passive implementation of complex analog filters used for image signal suppression. The general behavior of this class of networks, as well as their distinct property of discriminating between positive and negative sequences, are discussed and evaluated analytically. A design methodology is proposed and a sensitivity analysis based on Monte Carlo simulation is presented. The effect of the absolute variation of R and C values on the phase and gain matching, as well as on the image signal suppression, is also investigated for one-, two-, and three-stage networks.