This paper presents a K-band phase shifter with low insertion-loss variation fabricated with the TSMC standard 0.18-μm 1P6M CMOS technology. Low insertion loss variation is achieved by using impedance matching of the reflective load. To achieve a phase control range of 360°, a different 180° phase switch-type phase shifter (STPS) is applied to the output of a 180° continuous phase control range reflection-type phase shifter (RTPS). In this design, the layer of the bottom metal (M1) as the ground plane is used to minimize the substrate loss. The measured results show that the insertion loss variation in the phase control range is less than 1.2 dB, and the phase control range is 275° at 23 GHz. The chip size is 0.45 mm2 with pads and with no power consumption.