The need for low cost and low size radiometers have encouraged many to look at the implementation of radiometers using MMICs. Compared to their waveguide counterparts, radiometers implemented with MMICs significantly reduce the size and weight of the radiometer, while still maintaining satisfactory electrical performance at millimeter wave frequencies. Utilizing MMICs can also help in significantly lowering the noise temperature of the radiometer, specifically, metamorphic high electron-mobility transistors (mHEMT) have demonstrated very low noise, high gain performance and comparably low cost. This thesis is focused on designing a combined switch and low noise amplifier IC at 36.5 GHz that lowers the radiometer noise temperature while allowing for an accurate calibration. The measured gain from straight and 90 degree input of the switch-LNA, at 36.5 GHz, was 6.6 dB and 7.1 dB, respectively. Likewise, the noise figure of the MMIC was 3.8 dB and 3.3 dB, respectively. The mHEMT implemented SPDT switch has a measured insertion loss, at 36.5 GHz, of 1.3 dB and 0.88 dB with isolation of 25 dB and 36 dB, respectively. The calculated temperature sensitivity based on measured temperature variations was 0.273 K at 36 GHz.