A High‐Resolution Digitally Controlled Low‐Loss Reflective‐Type Analog Phase Shifter Based on a Single DAC

ABSTRACT This paper presents a digitally controlled reflective‐type phase shifter (RTPS) operating from 2.1 to 2.3 GHz, achieving a full 360° phase‐shift range using a single DAC. In conventional digitally controlled RTPS implementations, the achievable phase resolution is limited by the nonlinear capacitance–voltage characteristic of varactor diodes and the nonlinear relationship between phase and load reactance, resulting in uniform DAC voltage steps translating into non‐uniform phase increments. To mitigate this limitation while maintaining low circuit complexity, an 8‐bit uniform DAC is employed in conjunction with a phase‐code mapping strategy, where selected digital control codes are used to realize approximately uniform phase steps across the tuning range. The DAC output is multiplexed between two resonating load branches, enabling full‐range phase control using a single DAC and a single control line. The proposed RTPS achieves an approximately uniform phase‐shift resolution of about 3° ± 1° with low and stable insertion loss over the operating band. This approach provides a practical and robust solution for high‐resolution digitally controlled beamforming and phased‐array systems.