This paper presents a temperature compensated variable gain phase shifter (VGPS), composed of an active phase shifter followed by a variable gain amplifier (VGA). A temperature sensor adjusts the biasing of the phase shifter block and suppresses temperature effects on its insertion phase. Further, a self-compensation mechanism compensates the gain reduction at the VGA stage. The circuit is designed and laid out in 0.15 µm GaN HEMT. Post layout simulation results show that the proposed VGPS achieves over 180 °C of the relative phase shift for the frequency range of 4.5 to 5 GHz over the temperature ranging from 25 °C to 250 °C. The gain of the VGPS can be controlled from 5 dB to 20 dB.