Divide-by-four injection-locked frequency divider by using sub-harmonics mixer

A divide-by-4 injection-locked frequency divider (ILFD) with wide locking range is proposed. The divide-by-4 ILFD works by mixing the injection signal and the third harmonic. The frequency translation is given by ω_RF - 3ω₀ = ω₀. A new method is demonstrated by mixing the second harmonic with the fundamental signal to generate the required third harmonic. It is different from the conventional method by directly employing the third harmonic of the non-linear amplifier. The measured locking range is from 20.8GHz to 27.6GHz (28.1%) with an output power of -0.4dBm as the core-circuit taking a power consumption of 3.68mW from 1V power supply.