A mm-wave subharmonically injection-locked quadrature oscillator is demonstrated in a 40nm low-power (LP) digital CMOS technology. A large locking range (10GHz), tunable over the 52-66GHz band, is achieved using transformer-coupled resonators. A simple calibration scheme is proposed that only relies on a relative power measurement of the oscillator output signal. The wide locking range, the wide tunability and the simple calibration scheme make this injection-locked quadrature oscillator design suitable for frequency synthesis in mm-wave CMOS communication systems.