A 25-50 GHz Digitally Controlled Phase-Shifter

This paper presents the design and the implementation of a phase shifter based on cascaded reflection type phase shifters (RTPS). The RTPSs are based on a 90° hybrid coupler and varactors digitally controlled. By cascading the RTPSs the phase shift range and the bandwidth are increased. To compensate the quality factor variation of the varactor at millimeter-wave frequencies, a simple compensation technique which requires no additional control is used. The proposed 7-bit controlled phase shifter achieves 216° of phase shift range with a fine step of 1.7° and an RMS phase error of 0.3°, the insertion losses are 10.9 dB on average, for a bandwidth of 25-50 GHz.