A Bi-Directional Electronically Tunable CMOS Phase Shifter Using the High-Pass Topology

This paper presents an integrated phase shifter based on the high-pass L-C topology. The circuit utilizes both varactors and active inductors to extend the tuning range and achieve a low return loss. The high-pass topology results in a compact IC implementation, and allows phase compensation in series-fed antenna arrays utilizing this phase shifter. Furthermore, this approach allows integrating multiple stages on the same IC, without a significant size increase. A negative resistance is generated by the active inductor circuit, and is used to partially compensate the varactor losses. A test chip is fabricated in a standard 0.13 mum CMOS process, and a phase tuning range of 96deg is achieved at 4 GHz, with a return loss better than -18 dB across the entire tuning range. The phase shifter achieves a -2.2 dBm input compression point and a 7.4 dBm IIP3 while operating from a 1.5 V supply.