The design and performance of a Ka-band 5 b MMIC phase shifter using InGaAs PIN switching diodes is presented. In order to achieve low insertion loss and good phase shifting characteristics at Ka-band, a switched reactance type InGaAs PIN-diode phase shifter topology has been employed with a compact bias network. The fabricated InGaAs PIN MMIC phase shifter has demonstrated good performance characteristics such as a low insertion loss of less than 7.8 dB and a high P(1) dB of 21.0 dBm compared to the previous results.