RF self-interference cancellation (SIC) relaxes duplexer isolation requirements in frequency- division-duplex (FDD) radios, enabling compact/tunable duplexers. RF SIC is also critical for full-duplex radios where extremely-high levels of SIC must be achieved, necessitating SIC at various points in the receiver chain. While active RF SIC is potentially compact and highly reconfigurable, the use of active circuitry in the canceller introduces noise, distortion and power dissipation challenges. Furthermore, and particularly for fully-integrated silicon-based SIC implementations, the bandwidth (BW) of RF SIC is limited by the frequency selectivity of the antenna interface and the wireless self-interference channel. In this paper, we present recent developments in fully-integrated RF SIC techniques that address these challenges.