This paper investigates a dual-band vector-sum phase shifter operating at 5G millimeter-wave (mmW) bands. It is implemented in a 22nm FD-SOI technology to prove the concept. The phase shifter core is composed of a poly-phase-filter (PPF) for differential quadrature signal generation and an amplitude control block for vector amplitude tuning. An advanced phase compensation technique has been studied and applied to eliminate the degradation of the PPF phase accuracy due to circuit parasitics. Continuous 360° phase control is demonstrated at 28GHz and 38GHz. The proposed design achieves an average gain of about 5dB at 28GHz and 8dB at 38GHz at a total DC power of 19.5mW. The measured root-mean-square (RMS) amplitude-and phase-errors are 0.1dB and 1.3° at 28GHz and 0.1dB and 0.7° at 38GHz. To the best knowledge of the authors, this is the first dual-band vector-sum phase shifter operating at 5G mmW-bands in 22nm FD-SOI.