Design of a 5-bit CMOS phase shifter with tunable active inductors for 5G applications in S-band

This paper presents a 5-bit CMOS phase shifter integrating tunable active inductors to achieve compact size, wideband operation, and low phase error. Conventional inductors occupy large silicon area with low quality-factor. To overcome this, a Gm-boosted gyrator-C active inductor with resistive-feedback is used, operating up to 4.1 GHz. The design offers wide inductance tuning from 1.8 nH to 220 nH, improved quality factor, and reduced die area. The phase shifter operates between 2.2-3.6 GHz, with reflection coefficients below -10 dB, an RMS phase error below 3.3°, average insertion loss of 14 dB, and occupies an area of only 0.17 mm², making it ideal for compact phased arrays in radar and 5G systems.