A 44-52 GHz Reflection-type Phase Shifter with 1.4° Phase Resolution in 28nm CMOS Process

This paper presents a 44-52 GHz passive reflection-type phase shifter with high phase resolution in 28nm CMOS process. The circuit consists of a hybrid coupler and two π-network loads. In the π-network loads, variable capacitance is realized by the capacitor array. Compared with the previously reported 6-bit phase shifter with 360° phase shift range, the proposed phase shifter achieves 1.4° phase shift accuracy. Although the proposed phase shift range is 96°, it can be extended to an 8-bit 360° phase shifter by cascading a coarse-tuning phase switcher. Across the full operating band, the post-layout simulated RMS phase error is 0.15° and the post-layout simulated RMS gain error is 0.34 dB, and the chip core area is 300 μm × 270 μm.