A $K$ -Band Divide-by-Five Injection-Locked Frequency Divider Using a Near-Threshold VCO

This letter presents a divide-by-five injection-locked frequency divider (ILFD) using a near-threshold (NT) VCO. The input frequency is injected in the proposed ILFD by a VCO employing a noise-cancelling technique. Both the proposed ILFD and VCO are based on a single compact coil which consists of a distributed and center-tapped inductor for an enhanced ILFD locking range of 20.2 to 21.9 GHz without varactors. The proposed VCO and ILFD are fabricated in a 0.13 μm CMOS process and consume 0.3 and 0.55 mW, respectively, from a 0.45 V supply.