An 8.2-10.2 GHz Digitally Controlled Oscillator in 28-nm CMOS Using Constantly-Conducting NMOS Biased Switchable Capacitor

Abstract

This paper presents an 8.2-10.2 GHz digitally controlled oscillator (DCO) in a 28 nm technology. The proposed DCO utilizes a switchable capacitor (SC) structure with a constantly conducting NMOS pair, featuring an SC bank with unitary cells arranged in a matrix. With the unitary weighted capacitor bank, the DCO demonstrates an inherently monotonic tuning with a range of 24.3 %. The finest tuning resolution is 17 kHz thanks to the customized fringe capacitor. The DCO shows a phase noise of −115.1 dBc/Hz at 1 MHz offset from 9 GHz carrier frequency with 13 m W power consumption, achieving a −183 dBc/Hz FoM and −190.6 dBc/Hz $\mathbf{FoM}_{\mathrm{T}}$.