The fifth-generation (5G) mobile communication system is being developed to provide ultra-high-speed and large-capacity wireless communication services. However, due to the large transmission loss in the air for high-frequency signals, it is necessary to use large-scale array antennas to achieve adaptive control of antenna directivity to compensate for the loss. This paper reports a passive phase shifter operating at 23–28 GHz. The proposed 5-bit switch-type phase shifter with 1-bit calibration is designed in a 0.15-μm GaAs process. A new design method based on the optimized ABCD matrix and impedance matching techniques between a chip and a printed circuit board (PCB) is developed to obtain better radio-frequency (RF) signal transmission. The proposed phase shifter features a good-phase performance with a measured root-mean-square (RMS) phase error of less than 10° across 23–28 GHz. For all the phase shift states, the insertion loss is 18 ± 2 dB at 28 GHz and the RMS gain error is less than 2.1 dB over 23–28 GHz including pads and RF connector loss. The phase shifter consumes no DC power and occupies a chip area of 2 × 0.7 mm including all the pads.