A 3.5–4.5-GHz ultra-compact 0.25mm2 reflection-type 360° phase shifter

An ultra-compact reflection-type phase shifter (RTPS) with full 360° continuous phase shift and low insertion loss using standard 0.18-µm CMOS technology is demonstrated in this paper. Dual active reflection load using active inductor is utilized in the proposed reflection-type load to cover 360 ° phase tuning through only one quadrature hybrid, which has the advantages of compact chip size, low insertion loss, and low loss variation. Measurements show better than 15 dB input/output return loss, signal losses of 6.4dB±1.5dB, less than 2.4dB±0.6 dB loss variation, and a 360 ° continuously tunable range across 3.5∼4.5 GHz with 3.4mW dc power consumption. To the best of our knowledge, the proposed phase shifter has the smallest die size, 0.25 mm2, among all reported 360° C-band CMOS RTPS, which is important for a large phase array system.