To conclude, this work proposes a phase-shifter design based on all-pass networks. The advantage of the proposed phase shifter design is that it ideally exhibits zero reflections for both phase-shifting states. The design equations are derived and presented in this paper. The design concept is verified by a 90° phase shifter on a GaAs pHEMT process. Though we only demonstrate a 90° design in this paper, the design equations can be applied to any phase shift below 180°. Moreover, the proposed design exhibits excellent return losses for both phase-shifting states. Therefore, a multiple-bit phase shifter can be readily obtained by cascading several single-bit phase shifters based on the proposed design without further tuning.