A CMOS Vector-Sum Phase Shifter for 5G mm-Wave Application

This paper presents a wideband CMOS vector-sum phase shifter (VSPS) targeting the n260 band of 5G communication. A differential quadrature generator is implemented using a Marchand balun and two 90 degrees coupled-line couplers to improve robustness to process and temperature variations. The quadrature vector signals are combined by a following vector modulator that adopts a double Gilbert-cell topology. The linearity and input-matching performance are enhanced at the expense of extra DC consumption by stacking a current source with high bias. The measurement shows that the VSPS provides a continuous 360 degrees phase shift with an average insertion loss of 16.3 dB at 37 GHz. The root-mean-square (RMS) amplitude and phase errors maintain less than 1.5 dB and 4.9 degrees, respectively, from 30.9 GHz to 41.7 GHz. The input-referred 1-dB compression point is 5.7 dBm at 38 GHz. It is also demonstrated by 484-state measurement that the phase and amplitude can be adjusted in a fine resolution.