A 28 nm 8.2-11.1 GHz Class-C Digitally Controlled Oscillator with 40 kHz Tuning Resolution

This paper proposes a class-C digitally controlled oscillator (DCO) using constantly-conducting NMOS biased switchable capacitor, aiming to optimize the off-state quality factor, reduce the off-state capacitance and improve the oscillator transient behavior. The DCO is fabricated in a 28 nm CMOS technology. With a unitary-weighted SC bank, the DCO shows an inherently monotonic tuning with a range of 8.2-11.1 GHz (30.1%), and a very fine tuning resolution of 40kHz. The class-C DCO achieves -115.5 dBc/Hz phase noise at 1 MHz offset from 10 GHz carrier frequency with 23 mW, resulting in a -182 dBc/Hz FoM and -191.5dBc/Hz FoM
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