This letter presents a rotary travelling-wave oscillator (RTWO) with reliable direction control in a standard 130 nm complementary metal–oxide–semiconductor (CMOS) technology. To achieve low phase noise (PN), and low power consumption, 16-stages customised transmission line segments are designed and simulated on electromagnetic tools. The PN is investigated through modelling the RTWO as multiple standing-wave oscillators. The proposed oscillator achieves 11.2% tuning range, 190.3 dBc/Hz figure-of-merit (FoM) at 1 MHz offset and 192.3 dBc/Hz FoM at 10 MHz offset with 5.8-mW power consumption from 16-GHz carrier.