A 270 Hz, Fine Frequency Tuning Class-C Oscillator Using Capacitive--Inductive Degeneration Technique in 130 -nm CMOS

This paper presents a high-resolution Class-C type voltage-controlled oscillator (VCO) with a robust start-up. The proposed oscillator achieves a minimum frequency quantification step of 270 Hz without adding any additional dithering approach. The very fine tuning is obtained through a capacitive-inductive degeneration coupling (CIDC) technique which reduces the capacitance value without appreciably affecting the intrinsic oscillator phase noise (PN). This technique also provides a negative transconductance to compensate for losses in the LC tank, resulting in high oscillation amplitude and relatively low power consumption in the oscillator core. The proposed design, implemented in 130 nm CMOS technology, achieves 45% tuning range. It exhibits a phase noise of –107 dBc/Hz @ 1-MHz offset, while it draws 5.75 mA from a supply of 1.2 V, resulting in a FoM of 165 dBc/Hz.