This paper presents a novel active phase shifter circuit topology based on LC all-pass lattice filter with variable inductors and capacitors within an amplifier. By tuning properly the inductance and capacitance of the filter it is possible to shift the input signal by the desired amount of phase from 0° to 180°. The preliminary design of a 60-GHz 8-phase phase shifter with phase resolution 22.5° from 0° to 157.5° has been carried in 28nm FDSOI CMOS by STMicroelectronics in order to demonstrate the validity of the proposed idea.
Simulation results show an average gain of 15 dB at 60.8 GHz, a 3 dB bandwidth of 12 GHz, RMS gain error and RMS phase error lower than 1.8 dB and 12° in band. Simulations of the normalized gain pattern of a 4-element phased array with the proposed phase shifter show a deviation of the beam steering angle lower than 6° with respect to the ideal phase shifts.