A system for generating a radio frequency signal phase-locked to a reference signal. Such a system includes a rotary travelling wave oscillator including a conductive ring and a plurality of sustaining amplifying cells electrically connected to the ring; a programmable multiplexer device designed to electrically connect an input port of the system to an amplifying cell that can be selected from the cells of the plurality. The system is designed so that the oscillator generates the locked radio frequency signal when the reference signal is injected at the input port of the system. A phase difference between the radio frequency signal and the reference signal is a function of the amplifying cell to which the input port is electrically connected via the programming of the multiplexer device.