A frequency doubler is designed to provide the local oscillator signal to a 77 GHz automotive radar system in 22 nm fully-depleted silicon on insulator (FDSOI) CMOS. Circuit design techniques such as Gm-boosted cascode, inductive peaking and load-pull/source-pull optimization is used to increase the conversion gain (CG) and output power of the circuit without requiring additional dc power. The back-gate control feature of the FDSOI process is employed as well for CG boosting. The frequency doubler delivers up to 5.5 dBm of output power in the 76–81 GHz band at a maximum power added efficiency (PAE) of 7.3 %. To the best knowledge of the authors, the peak conversion gain of 14 dB is among the highest reported for doublers in CMOS operating in the frequency range of the 77 GHz radar.