A 33.5–92.6-GHz CMOS Injection-Locked Frequency Divider Using Fourth-Order Resonator

This letter presents a novel fourth-order resonator for millimeter-wave (mmW) wideband injection-locked frequency divider (ILFD) in 40-nm CMOS. To operate at high frequencies, such as E-band, and obtain wide locking range (LR) simultaneously, the fourth-order transformer is intentionally designed with high coupling coefficient and low quality factor of secondary coil to achieve a flat and broad impedance response. The measurement results demonstrate an LR of 59.1 GHz from 33.5 to 92.6 GHz, with a fractional bandwidth of 93.7%. The chip features a compact core area of 0.0165 mm2 ( $0.0007\lambda ^{2}$ ) and consumes 6.18 mW from a 0.6-V voltage supply.