A 14.5-17.9 GHz Harmonically-Coupled Quad-Core P-N Class-B DCO with -117.3 dBc/Hz Phase Noise at 1 MHz Offset in 28-nm CMOS

In this paper, a CMOS quad-core DCO with class-B operation and transformer-based tail coupling is investigated to achieve ultra-low phase noise in the Ku band. The design uses an averaging approach to minimize systematic frequency step errors arising in DCOs with large tuning capacitor arrays due to signal unequal distribution. A proof-of-concept prototype has been developed in 28-nm CMOS technology. The DCO achieves a phase noise of−117.3 dBc/Hz at 1 MHz offset from the 15.35 GHz carrier frequency, a figure of merit (FoM) of -187.6 dBc/Hz, and a tuning range of 20.3% with a frequency resolution of 10MHz and less than ±240 kHz error.