A W-band injection-locked frequency tripler (ILFT) with transformer-coupled topology is implemented in 90-nm CMOS process in this paper. By using the transformer-coupled topology, this proposed frequency tripler can achieve wider locking range with lower dc power consumption than varactor tuning LC-Tank. The measured output locking range is up to 15% frequency bandwidth from 75 to 87 GHz for the input power of 0 dBm, which has differential input from 25 to 29 GHz through a Marchand balun. The average output power is around-26 dBm over the entire locking range, while consuming 3.7 mW at 0.7-V supply voltage. The measured phase noise is-90 dBc/Hz at 1MHz offset frequency and the free-running frequency is 78.9 GHz. The chip area is 0.806 × 0.660 mm2. To the best of authors' knowledge, the proposed ILFT has the widest locking range under low dc power consumption.