A Ka-band CMOS Active Phase Shifter Using Active Balun for Phase Optimization

In this paper, we designed a CMOS active phase shifter that operates in the Ka-band. In the active phase shifter, the differential signals with high phase accuracy were generated using active balun to alleviate complexity, thereby reducing the insertion loss of I/Q generator. In addition, we proposed a layout technique that can secure symmetry between the output signals of poly phase filter (PPF). To verify the feasibility of the proposed design technique, we designed an Ka-band active phase shifter using 65 nm RFCMOS process. The core size of the designed phase shifter was 0.506 x 0.257 mm(2). At the target frequency of 28 GHz, the measured RMS phase and gain errors were lower than 0.35 degrees and 0.07 dB, respectively.