A microwave PIN diode 4-bit phase shifter is designed in X-band. A loaded-line type is used for the 22.5$^{circ}$ and 45$^{circ}$ bits, and a switched-line type for the 90$^{circ}$and 180$^{circ}$bits. The measured results show that the phase error and average insertion loss are less than $pm$5.4$^{circ}$and 7.2dB, respectively, over a 9.75~10.25GHz frequency band.