Abstract:The digital phase shifter is widely used in phased-array radar. The phase shifter was fabricated using tandem stub for 11.25°,22.5°and 45°, and using 3 dB branch-line coupler type for 90°and 180°. A 5-bit digital phase shifter circuit in Ka-band was presented. The measurement results indicated that the maximum of the phase error was 6.5°，the minimum of the phase error was 0.2°, the maximum of insertion loss was 11.8 dB, the minimum of insertion loss was 8.6 dB, and the VSWR was better than 2 in the frequency band of 30 GHz-31 GHz. The whole volume of the phase shifter was 110 mm× 55 mm×25 mm.