Frequency-modulated continuous-wave (FMCW) radars can provide high resolution and superior sensitivity for wireless sensing [1-3]. Radar signals, whose frequency increases or decreases linearly with time, are transmitted via an antenna, reflected from an object, and then received through an antenna after a time delay. Therefore, the frequency difference between the transmitted and received signals can define the distance and speed of objects. There are two approaches of interfacing antenna for a FMCW radar, namely two-antenna (i.e. separated-antenna) and single-antenna (i.e. shared-antenna) methods. A single-antenna FMCW radar is more compact, but more difficult to implement than a two-antenna one. On-chip in-band full duplexers (IBFDs) with a self-interference cancellation mechanism can support general integrated single-antenna wireless systems [4-6]. For the specific application of a FMCW radar, a duplex RF front-end without the complexity of on-chip IBFDs has been proposed. With it, an integrated FMCW radar is allowed to transmit and receive simultaneously via a single antenna. In this work, an integrated X-band FMCW radar chip is implemented in 65nm CMOS and a wireless demonstration of the radar chip is presented.