A 9.3MHz to 5.7GHz tunable LC-based VCO using a divide-by-N injection-locked frequency divider

This paper proposes a novel wideband voltage-controlled oscillator (VCO) for multi-band transceivers. The proposed oscillator has a core VCO and a tuning-range extension circuit, which consists of an injection-locked frequency divider (ILFD), and flip flop dividers. The 2-stage differential ILFD can generate quadrature outputs, and it realizes 2, 3, 4, and 6 of divide ratio with very wide output frequency range. The proposed circuit is implemented by using a 90 nm CMOS process, and the chip area is 250 ¿m × 200 ¿m. The measured results achieves 9.3 MHz-to-5.7 GHz (199%) of continuous frequency tuning range with -210 dBc/Hz of FoM_T.