An integrated X-band FMCW front-end is reported. The front-end unites the core functionality of an FMCW transmitter and receiver in a 0.25 µm SiGe BiCMOS process. The chip integrates a PLL for the carrier generation, and single-side band and image-reject mixers for up- and down-conversion of the waveform. The front-end has been designed to co-operate with COTS integrated direct digital synthesisers and ADCs. The measurements show an output power of 0 dBm, P 1dB at the receiver input of −11 dBm and a side band suppression of the mixer in the transmit chain of >40 dBc. The MMIC measures 1.8×1.5 mm 2 . This integrated front-end paves the path for future planar 2D integration of FMCW phased-array radars at X-band.