A Tunable Metamaterial Phase-Shifter Structure Based on a 0.13μm CMOS Active Inductor

This paper presents a novel tunable metamaterial-based phase-shifter structure utilizing active circuits. It comprises a microstrip transmission line loaded with series varactors and tunable active shunt inductors to increase the phase tuning range and maintain the input & output matching of the metamaterial phase shifter. The proposed phase shifter is capable of providing both a positive and negative phase shift. The active inductors are fabricated in a 0.13μm CMOS process and operate from a 1.5V supply, a 1:2.9 inductance tuning range is measured at 2.5GHz with a tunable peak quality factor ≥ 100. The performance of the metamaterial phase shifter unit-cell is simulated using the measured active inductor S-parameters, it achieves a phase tuning range of ± 20° at 2.5GHz, with < 0.6dB insertion loss and better than -30dB reflection loss.