A Wideband Active Phase Shifter using Positive and Negative Inductance/Capacitance

This letter presents an active phase shifter providing a quasi-constant transmission (S
₂₁
) phase over a wide frequency range. The active phase shifter consists of positive and negative inductance/capacitance(L/C). The transmission phase of the positive L/C is compensated by that of the negative L/C along the frequency. The active phase shifter was implemented in IBM 7RF 180 nm CMOS technology. The measured transmission phase ranged between -70° and -110° with a minimum phase variation of 10°, and the insertion loss ranged between 4 and 6 dB from 1.2 to 2.8 GHz. The size of the core chip was 650 × 800 μm
²
.